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d^titvtntt  Hihvavp 


A  MANUAL 


HYGIENE  AND  SANITATION. 


BY 

SENECA  EGBERT,  A.M.,  M.D., 

PEOFESSOE  OF  HYGIENE  AND  DEAN  OP  THE  MEDICO-CHIEURGICAL  COLLEGE 

OF  PHILADELPHIA;    MEMBER  OP  THE    ACADEBIY   OF    NATURAL 

SCIENCES  OP  PHILADELPHIA  ;   MEMBER  OF  THE 

AMERICAN  MEDICAL  ASSOCIATION, 

ETC.,  ETC. 

FOURTH  EDITION,  ENLARGED  AND  THOROUGHLY  REVISED. 
ILLUSTRATED  WITH   93   ENGRAVINGS. 


LEA   BROTHERS   &  CO., 

PHILADELPHIA    AND    NEW    YORK. 


"R^^^B 


Entered  according  to  the  act  of  Congress,  in  the  year  1907,  by 

LEA  BROTHERS  &  CO., 

In  the  Office  of  the  Librarian  of  Congress.    All  rights  reserved. 


WESTCOTT    &    THOMSON,  PRESS    OF 

ELECTROTVPERS.   PHILAOA.  WILLIAM    J.   OORNAN,    PHILADA. 


TO  THE 

MEMORY  OF  MY  FATHER, 

TO   WHOM   I   OWE   SO   MUCH;   TO   WHOM  I   COtlLD   REPAY  SO   LITTLE, 

THIS  VOLUME 

IS    MOST    AFFECTIONATELY 

DEDICATED, 


Digitized  by  tine  Internet  Arciiive 

in  2010  witii  funding  from 

Open  Knowledge  Commons 


http://www.archive.org/details/manualofhygienes1907egbe 


PREFACE  TO  THE  FOURTH  EDITION. 


The  reception  accorded  to  this  work  has  seemed  to 
indicate  that  it  filled  a  place  in  the  literature  of  its  sub- 
ject, and  therefore  in  revising  it  for  a  new  edition,  its 
scope,  size,  and  characteristics  have  been  maintained. 
Every  sentence  has  been  reviewed,  certain  parts  have 
been  rewritten,  and  throughout  such  changes  have  been 
made  as  Avere  necessary  to  represent  the  subject  in  its 
latest  development.  About  twenty  pages  have  been  added 
to  cover,  among  other  matters,  the  theory  of  opsonins  in  its 
relation  to  immunity,  the  latest  regulations  of  the  United 
States  Government  in  regard  to  quarantine  and  disin- 
fection (for  which  the  author  is  indebted  to  Dr.  Walter 
Wyman,  Surgeon-General  of  the  Public  Health  and 
Marine  Hospital  Service),  and  notes  on  improved  methods 
of  disposal  of  sewage. 

Moreover,  the  data  on  the  vital  statistics  of  the  country, 
and  of  some  of  its  great  cities,  have  been  revised  to  include 
the  figures  given  in  the  latest  reports  of  the  United  States 
Census  Bureau  and  the  various  municipal  boards  of  health. 
Such  data  are  especially  instructive  and  important,  since 
they  show  most  positively  that  the  vital  status  of  the 
people  of  this  country  is  continually  improving  as  a  re- 
sult of  the  general  and  progressive  education  in  and  appli- 
cation of  the  principles  of  hygiene. 

The  author  is  fully  cognizant  of  what  may  seem  to 
be  omissions,  but,  as    stated,  the  scope  and  size  of  the 


6  PREFACE  TO   THE  FOURTH  EDITION. 

work  have  precluded  their  introduction.  The  science  of 
Hygiene  has  become  so  extensive  that  many  volumes 
might  be  devoted  to  the  discussion  of  its  principles  and 
the  details  of  their  application.  Consequently,  the  anthor 
will  be  content  if  the  book  continues  to  serve  its  purpose 
as  a  simple  "  manual."  He  takes  this  opportunity  to 
express  his  appreciation  of  the  kindly  and  generous  man- 
ner in  which  the  previous  editions  have  been  received  by 
their  critics  and  readers,  and  to  hope  that  the  present  one 
may  have  the  same  reception  as  its  predecessors. 

S.  E. 
Philadelphia,  1907. 


CONTENTS, 


CHAPTER  I. 

PAGE 

Introduction - 17 

CHAPTER  II. 
Bacteriology 36 

CHAPTER  III. 
The  Atmosphere— Air 70 

CHAPTER  IV. 
Ventilation  and  Heating 103 

CHAPTER  V. 
Water 147 

CHAPTER  VI. 
Food 221 

CHAPTER  VII. 

Stimulants  and  Beverages 270 

CHAPTER  VIII. 
Personal  Hygiene 279 

CHAPTER  IX. 
School  Hygiene 310 

CHAPTER  X. 

Disinfection 329 

7 


8  CONTE^'TS. 

CHAPTER  XL 

PAGE 

Quarantine .    .    302 

CPIAPTEE  XII. 
The  Removal  and  Disposal  of  Sewage 382 

CHAPTER  XIII. 
Military  Hygiene 422 

CHAPTER  XIV. 
Vital  Statistics 443 

CHAPTER  XV. 
The  Examination  of  Air,  Water,  and  Food 458 


A  xMNUAL  OF  HYGIENE  AND  SANITATION. 


CHAPTER   I. 

INTKODUCTION. 

Hygiexe  may  be  defined  as  the  art  and  science  that 
considers  the  preservation,  promotion,  and  improvement 
of  health  and  the  prevention  of  disease.  It  treats  of 
the  laws  of  health  in  the  broadest  sense,  and  under  the 
sreneral  term  mav  be  included  a  number  of  subdivisions. 
Thus,  while  Personal  and  Domestic  Hygiene  are  respec- 
tively more  closely  related  to  the  affairs  of  the  individual 
and  the  household,  Sanitary  Science  also  finds  larger  fields 
and  broader  application  in  the  domain  of  State  Medicine 
and  the  Hygiene  of  Municipalities. 

A  little  thought  will  show  tliat  under  the  general  head 
we  may  consider:  1.  The  preservation  and  promotion  of 
health.  2.  Practical  disinfection  and  the  means  of  avoid- 
ing preventable  diseases.  3.  Adaptation  of  diet  and  other 
factors  to  the  prevention  and  cure  of  perversions  of  nutri- 
tion. Under  one  or  another  of  these  themes  will  fall  the 
discussion  of  the  air  we  breathe,  the  Avater  we  drink,  the 
food  we  eat,  the  soils  and  surroundings  of  our  dwellings 
and  communities  ;  and  at  the  same  time  the  study  of  the 
means  of  recoi;:nizin(j,  avoidino;,  correcting:,  or  removinor 
all  impurities  affecting  any  of  these.  In  addition,  there 
2  17 


18  IN  TROD  UCTION. 

must  be  the  study  of  climate  and  meteorology;  of  clothing 
and  shelter ;  of  the  care  of  the  sick,  not  only  for  their  own 
sake,  but  that  they  may  not  endanger  the  well ;  the 
dangers  of  the  abuse  of  stimulants,  narcotics,  etc. ;  tlie_ 
desirability  of  chaste  and  teraperate_2iying,  exercise, 
rest,  etc.        -— p— — — -^ 

Parkes  says  that,  "  taking  the  word  '  hygiene '  in  its 
largest  sense,  it  signifies  rules  for  the  perfect  culture  of 
mind  and  body.  It  is  impossible  to  dissociate  the  two. 
The  body  is  affected  by  every  mental  or  moral  action ; 
the  mind  is  profoundly  influenced  by  bodily  conditions. 
[So  is  the  moral  conduct  of  individuals  or  communities.] 
For  a  perfect  system  of  hygiene  we  must  train  the  body, 
the  intellect,  and  the  moral  faculties  in  a  perfect  and  bal- 
anced order."  Again,  he  says :  "  Looking  only  to  the 
part  of  hygiene  which  concerns  the  physician,  a  perfect 
system  of  rules  of  health  would  be  best  arranged  in  an 
orderly  series  of  this  kind.  The  rules  would  commence 
with  the  regulation  of  the  mother's  health  while  bearing 
her  child,  so  that  the  growth  of  the  new  being  would  be 
as  perfect  as  possible.  Then,  after  birth,  the  rules  (dif- 
ferent for  each  sex  at  certain  times)  would  embrace  three 
epochs :  of  growth  (including  infancy  and  youth) ;  of 
maturity,  when  for  many  years  the  body  remains  appar- 
ently stationary  ;  of  decay,  when,  without  actual  disease, 
though  doubtless  in  consequence  of  some  chemical  changes, 
molc^cular  feobl(Miess  commences  in  some  part  or  other, 
forcruTiniiig  general  decay  and  death.  In  these  several 
epochs  of  his  life  the  human  being  would  have  to  be  con- 
sidered :  Fird^  in  relation  to  the  natural  conditions  which 
surround  him,  and  which  are  essential  for  lif(\  such  as  the 
air  he  breathes,  the  water  he  drinks,  etc.  ;  in  fact,  in  rela- 
tion to  nature  at  large.    Second,  in  his  social  and  corporate 


SCOPE  OF  THE  SCIENCE.  19 

relations,  as  a  member  of  a  community  with  certain  cus- 
toms, trades,  etc.  ;  subjected  to  social  and  political  influ- 
ences, sexual  relations,  etc.  Third,  in  bis  capacity  as  an 
independent  being,  having  within  himself  sources  of 
action,  in  thoughts,  feelings,  desires,  personal  habits,  all 
of  which  affect  health,  and  which  require  self-regulation 
and  control.  Even  now,  incomplete  as  hygiene  is,  such 
a  work  would,  if  followed,  almost  change  the  face  of  the 
world." 

The  student  will  readily  see  that  the  scope  of  the 
science  is  so  vast  that  in  a  limited  work  like  the  present 
one  it  would  be  impossible  to  go  over  the  entire  ground 
completely  and  thoroughly.  The  most  that  may  be 
attempted  will  be  to  discuss  its  fundamental  laws  as  we 
now  understand  them,  especially  those  that  are  most 
closely  connected  with  the  conscientious  physician's  duties 
and  practice,  and  to  show  the  reasons  for  and  the  advan- 
tages resulting  from  the  pursuit  of  hygienic  measures  and 
sanitary  methods  based  on  those  laws  and  our  experi- 
ence. Hygiene  is,  however,  a  science  in  the  study  of 
which  common-sense  must  be  freely  used ;  and  if  the 
student  will  only  bring  this  to  his  aid  and  add  to  it 
sincere  attention,  he  will  speedily  find  that  there  is  little 
that  is  difficult,  beyond  his  grasp,  or  less  than  really  fas- 
cinating. 

It  has  always  been,  as  it  always  will  be,  an  art  to  pre- 
serve health  and  to  ward  off  disease.  Hippocrates  was 
among  the  first  to  define  principles  of  public  health  or 
sanitation.  He  summed  up  the  knowledge  of  his  day 
concerning  hygiene  under  six  headings,  viz. :  Air,  Ali- 
ment, Exercise  and  Rest,  Sleep  and  Wakefulness,  Reple- 
tion and  Evacuation,  and  the  Passions  and  Affections  of 
the  Mind ;  and  he  even  pointed  out  that  there  must  be 


20  INTROD  UCTION. 

an  exact  balance  between  food  and  exercise,  and  that 
"  disease  would  result  from  excess  in  either  direction."  ^ 

The  excellence  of  the  Mosaic  code  is  acknowledged  by 
all  sanitary  authorities,  and  the  effects  of  its  observance 
are  seen  to  this  day  in  the  comparative  longevity  of  the 
Hebrew  race.  The  Greeks  cultivated  to  the  extreme  both 
the  physical  and  mental  faculties,  and  had  for  their  motto, 
A  sound  mind  in  a  sound  body.  The  Romans,  in  their 
aqueducts  for  conveying  water  to  the  city  and  in  the 
Cloaca  Maxima,  have  left  examples  of  sanitary  engineer- 
ing which  are,  in  certain  respects,  not  yet  surpassed. 
All  of  which  serves  to  show  that  the  ancients  appre- 
ciated the  importance  of  maintaining  and  improving 
health,  and  the  influence  of  material  conditions  and 
environment  upon  sanitation. 

The  development  of  hygiene  as  a  science,  however,  has 
been  within  comparatively  recent  years.  Perhaps  the 
first  great  impulse  among  English-speaking  peoples,  espe- 
cially in  matters  pertaining  to  sanitation  or  "  State  Medi- 
cine," can  be  traced  to  the  labors  of  Dr.  William  Farr, 
and  to  the  establishment,  through  his  efforts,  of  the 
British  Registrar-General's  Office  in  1838.^  Since  then 
the  task  of  determining  the  principles  and  laws  of  health 
has  been  carried  on  with  unflagging  zeal  by  workers  both 
here  and  abroad,  and  within   the  last  score  of  years  or 

^  Treatise  on  Airs,  Waters,  and  Places.  (About  400  B.  C.) 
^  Note  should  be  made,  however,  cf  the  writings  of  Johannes  Petrus 
Frank,  in  the  first  quarter  of  the  nineteenth  century  and  even  earlier, 
and  of  Parent  DiiChateh^t,  between  1820  and  1836.  Of  the  work  of  the 
former,  it  has  been  said  that  "It  was  the  first  orderly  presentation  of 
that  which  had  hitherto  been  known  upon  these  subjects,  and  was  the 
first  systematic  effort  to  rescue  from  chaos  such  useful  information  as 
miglit  be  of  service  in  the  organization  of  a  department  of  sanitary 
supervisors,  or,  as  tbo  author  preferred  to  call  them,  medical  police." 
A.  C.  Abbot-t,  University  Medical  Magazine,  July,  1900. 


VALUE   OF  SANITATION.  21 

less  the  knowledge  gained  in  the  new  study  of  the  bac- 
teria, especially  that  regarding  the  causation  and  nature 
of  infectious  diseases,  has  furnished  us  with  a  w^ealth  of 
facts  with  and  by  which  we  may  make  the  foundations  of 
our  science  more  secure  and  lasting. 

It  would  be  wrong,  nevertheless,  to  give  the  impression 
that  hygiene  is  as  yet  an  exact  science.  While  it  is 
rapidly  attracting  popular  notice  and  attention,  and  has 
attained  within  comparatively  recent  years  a  dignity  that 
it  did  not  hitherto  have  in  this  new  world,  it  is  on  a 
somewhat  firmer  basis  in  the  older.  The  brightest  minds 
of  the  day  are  busy  with  many  of  its  problems,  and 
facts  and  laws  are  being  made  clear  that  more  firmly  fix 
or  may  altogether  change  some  of  our  beliefs  and  our 
practice.  Especially  is  such  new  knowledge  to  be  sought 
for  in  the  study  of  the  prevention  of  disease,  the  domain 
of  bacteriology,  the  parasitic  diseases,  and  the  chemistry 
of  the  animal  alkaloids  and  kindred  compounds. 

Perhaps  a  few  statistics  will  help  one  to  realize  that  the 
study  is  not  in  vain,  and  that  the  promise  of  the  future  is 
even  more  brilliant  than  the  results  and  achievements  of 
the  past.  Three  centuries  ago  the  death-rate  of  London 
was  more  than  80  per  1000;  now  it  is  about  20  per 
1000.  It  is  computed  that  in  the  eighteenth  century — 
the  one  preceding  the  introduction  of  vaccination — fifty 
millions  of  people  died  in  Europe  of  smallpox  alone  ; 
now  it  is  practically  almost  an  extinct  disease  where  vac- 
cination is  compulsory,  as  in  Germany.  In  1872  Sir 
John  Simon  estimated  "  that  the  deaths  which  occur  in 
England  are  fully  a  third  more  numerous  than  they 
would  be  if  our  existing  knowledge  of  the  chief  causes 
of  disease  were  reasonably  well  applied  throughout  the 
country,  and  that  of  deaths  which  in  this  sense  may  be 


22  lyTRODUCTIOy. 

called  ])revental)le  the  average  yearly  number  in  Eng- 
land and  Wale-  i.<  abniit  120,000."  In  confirmation 
of  the  accuracy  of  this  statement,  official  reports  show 
that  the  annual  death-rate  of  Englaud  and  Wales,  which 
averaged  22.6  per  1000  for  the  decade  from  1862  to  1871 
inclusive,  fell  to  18.9  for  1881,  this  giving  a  saving  of 
02,000  lives  annually ;  while  for  1889,  even  with  the  cor- 
rection for  the  lowered  birth-rate,  it  was  only  17.9,  indi- 
cating a  yearly  saving  of  at  least  125,000  lives,  and 
completely  substantiating  the  above  estimate  of  Simon.^ 
Moreover,  the  death-rate  from  the  seven  principal  zymotic 
(infectious)  diseases  had  dropped  from  an  average  of  4.11 
for  the  period  from  1861  to  1870  to  2.40  for  1881-1885, 
and  that  from  typhoid  fever  from  0.39  i)er  1000  in  1869 
to  0.089  in  1905.  This  for  England  and  Wales.  In 
Munich  from  1866  to  1881  the  average  yearly  hospital 
admissions  of  typhoid  fever  cases  were  594,  or  3.32  per 
1000  of  population,  and  the  average  deaths  from  this  dis- 
ease were  208,  or  1.15  per  1000.  From  1881  to  1888, 
following  the  introduction  of  improved  systems  of  sewer- 
age and  a  better  water-supply,  the  average  hospital  ad- 
missions (typh(.id)  were  104,  or  0.42  per  1000,  and  the 
average  deaths  were  40,  or  0.16  per  1000  of  population. 

In  this  country  a  like  improvement  is  to  be  noted, 
though  it  is  onlv  within  the  last  few  decades  tliat  much 
attention  has  been  given  to  sanitary  affairs.  The  death-, 
rate  of  most  of  our  cities  is  l^eing  progressively  lowered, 
though  the  populations  are  constantly  increased  by  large 
numbers  of  ignorant  and  uncleanly  immigrants.  Im- 
])roved  sanitary  laws  are  being  enacted  and  enforced, 
streets  Ijetter  paved  and  cared    for,  houses    more  wisely 

'  Time  continues  to  lower  tlie  general  death-rate  for  these  countries, 
the  average  for  the  four  years.  1900  to  1904,  being  16.6,  and  that  for  1905 
alone,  1.5.2  per  1000  of  population. 


RECENT    VITAL  STATISTICS.  23 

constructed  and  ventilated,  more  attention  o;iven  to  iso- 
lating the  sick  and  protecting  the  well,  and  the  people 
in  general  are  awakening  to  the  importance  of  improv- 
ing as  well  as  maintaining  the  pnblic  health.  New  York 
City  has  reduced  her  death-rate  per  thousand  within 
the  last  fifteen  years  (1890  to  1905)  from  25.4  to  18.39  ; 
Chicago,  from  19.1  to  13.84;  Philadelphia,  from  20.76 
to  17.68  ;  Boston,  from  23.4  to  18.45,  etc.^ 

According  to  the  latest  United  States  Census  Report,^ 
in  New  York  City  (Manhattan  Borough)  there  were 
actually  4780  fewer  deaths  in  1900  than  in  1891  ;  in  Cin- 
cinnati, 1200  less ;  in  Buffalo  1000,  and  in  Albany  600 
less  in  the  later  than  in  the  earlier  year,  with  similar 
encouraging  reports  from  many  other  cities,  whose  authori- 
ties attribute  the  good  results  as  being  due  to  advance  in 
medical  and  snrgical  knowledge  along  the  lines  of  pre- 
ventive medicine,  improved  sanitary  surroundings,  im- 
proved water-supplies,  cleaner  streets,  inspection  of  milk- 
and  food-supplies,  isolation  and  modern  treatment  of 
infectious  diseases,  additional  public  parks,  etc. 

A  later  report  tells  us  that  in  the  so-called  "  registra- 
tion-area," which  embraces  24,358,177  of  the  total  urban 
population  of  the  United  States  living  in  cities  of  8000 
population  or  more,  and  9,399,634  of  the  total  rural  popu- 
lation, and  in  which  the  statistics  are  fairly  reliable  and 
the  death-rates  comparable, — that  in  this  area  the  death- 
rate  from  diphtheria  has  fallen  from  70.1  per  100,000  of 
population  in  1890  to  19.9  in  1905  ;  from  scarlet  fever, 

'  The  importance  of  such  statistics  is  not  fully  appreciated  unless  the 
reader  rememhers  that  in  a  city  of,  say,  a  million  inhabitants  a  reduc- 
tion of  the  death-rate  one  point  means  the  saving  of  one  thousand  lives 
annually. 

^Twelfth  Census  of  the  United  States,  1900,  vol.  iii.,  Vital  Statistics, 
Part  I. 


24  INTRODUCTION. 

from  13.6  to  6.8 ;  from  malarial  fever,  from  22.1  to  3.9  ; 
from  typhoid  fever,  from  46.3  to  28.1  ;  and  from  con- 
sumption, from  245.4  to  168.2  per  100,000  of  population. 
For  the  registration-area,  the  general  death-rate  has  fallen 
from  19.6  per  1000  in  1890  to  16.2  per  1000  in  1905, 
and  this  reduction,  if  applicable  to  the  whole  country,  with 
an  estimated  population  of  80  millions,  would  represent  a 
saving  of  272,000  lives  annually.  It  does  actually  repre- 
sent an  annual  saving  in  the  registration-area,  whose  pop- 
ulation in  1905  was  36,846,981  of  approximately  125,280 
lives.  Who  then  shall  say  that  the  study  and  practice  of 
hygiene  and  sanitation, — of  preventive  medicine  is  of  no 
practical  value  ?^ 

Nevertheless,  there  is  still  much  to  be  done.  Tuber- 
culosis, which  is  said  to  cause  from  one-seventh  to  one- 
fourth  of  all  the  deaths  in  the  civilized  world,  is  practi- 
cally a  preventable  disease,  and  we  now  not  only  know  its 
cause,  but  also  have  efficient  means  for  cure  in  a  large 
proportion  of  cases,  as  well  as  for  its  general  prevention. 
So  with  a  number  of  the  other  infectious  diseases.  Almost 
every  day  marks  an  increase  in  our  knowledge  of  their 
etiology  and  the  securing  of  immunity  from  them  ;  and 
not  only  must  physicians  make  use  of  this  knowledge 
as  they  acquire  it,  and  employ  their  utmost  endeavors  to 
secure  the  enactment  and  enforcementof  sanitary  laws  and 
regulations,  but  they  must  also  realize  that  a  large  part  of 

1  It  will  be  well  to  note  at  this  point  the  roavked  reflex  influence 
that  the  adoption  of  an  accurate  or  improved  method  for  the  registra- 
tion of  vital  statistics  has  upon  the  sanitary  status  of  any  part  of  the 
population.  Wherever  a  city  or  a  State  has  adopted  such  a  method  there 
has  almo.st  immediately  followed  an  improvement  in  its  morbidity-  and 
mortality-rates,  for  whi(;h  reason  the  conditions  obtaining  in  the  com- 
ponent parts  of  the  total  "  rcRistration-area"  of  the  United  States  are 
undoubtedly  better  than  in  similar  or  comparable  portions  of  the  re- 
mainder of  the  country. 


COSTINUOUS  PROPHYLAXIS  NECESSARY.        25 

their  work  lies  in  the  enlightenment  and  education  of  the 
people  in  all  matters  pertaining  to  the  public  health.^ 

The  plague  that  was  the  bane  of  Europe  centuries  ago, 
and  that  has  been  a  scourge  to  Asia  since,  still  threatens  us, 
occasionally,  at  our  western  gates,  and  is  rife  in  some  of 
our  newly  acquired  colonial  possessions.  The  infectivity 
of  pneumonia  is  not  appreciated  by  the  laity  nor  by  many 
physicians.  In  Chicago,  in  the  first  five  months  of  1903, 
there  were  more  than  twice  as  many  deaths  from  this  dis- 
ease than  from  consumption,  and  more  than  133  per  cent. 
more  than  from  all  other  communicable,  contagious,  or 
infectious  diseases.  We  must  not  forget  that  this  disease, 
which  can  be  so  pestilent,  is  "  more  or  less  limited  to  cen- 
tres, corresponding  in  the  main  to  the  most  densely  popu- 
lated areas,  with  their  allied  conditions  of  squalor  and 
poverty,"  ^  and  that  it  is  our  duty,  and  for  our  own  safety, 
to  improve  the  sanitary  conditions  and  environments  of 
such  areas  and  centres.  With  our  present  knowledge  of 
the  value  of  vaccination,  there  have  been  far  too  many 
epidemics  of  smallpox  in  the  past  few  years.^  Careless- 
ness in  the  application  of  protective  measures  has  cost 
many  lives  and  much  money.     There  can  be  no  safe  ces- 

1  It  is  encouraging  to  find  that,  although  12  per  cent,  of  the  whole 
number  of  deaths  recorded  in  Philadelphia  in  1900  were  caused  by  con- 
sumption, a  progressive  and  marked  lowering  of  the  death-rate  from 
this  disease  in  that  city  is  taking  place,  and  that,  notwithstanding  an 
increase  in  population  of  over  48.3  per  cent.,  the  fatalities  from  this  dis- 
ease are  not  much  greater  in  number  than  they  were  sixteen  or  seven- 
teen years  ago.  For  example,  the  deaths  from  pulmonary  tuberculosis 
in  1885  numbered  2821,  and  in  1886  were  2834,  rates  respectively  of  2.97 
and  2.92  per  1000  living  ;  while  in  1904  there  were  only  3117  deaths,  or  a 
rate  of  2.22  per  1000  living. 

^  Anders,  Journal  of  American  Medical  Association,  May  9,  1903. 

•''  The  deaths  from  smallpox  in  the  registration-area  of  United  States 
for  the  year  1900  to  1904.  inclusive,  numbered  5.898,  this  representing 
an  average  annual  death-rate  of  3.7  per  100,000  of  population. 


26  INTRODUCTIOX. 

sation  in  prophylactic  eiforts.  So,  also,  eacli  and  every 
one  of  the  communicable  maladies  must  be  continually 
investigated  and  studied,  and  all  positive  information 
gained  concerning  them  must  in  turn  be  imparted  to  the 
people  who  need  protection  against  them. 

Order  of  Study. — In  the  preparation  for  a  study  like 
the  one  on  which  we  are  about  to  enter  there  is  some  ques- 
tion as  to  just  what  may  be  the  most  advantageous  order 
and  arrangement  of  the  subjects  to  be  treated.  For  in- 
stance, it  would  be  interesting  to  discuss  our  science  in  its 
relation,  in  turn,  to  the  individual,  the  household,  and  the 
people  in  general — that  is,  personal,  domestic,  and  public 
hygiene;  and  to  show  wherein  the  treatment  of  these  sub- 
divisions is  similar  and  wherein  they  diifer.  Such  a  three- 
fold consideration  would  be  not  only  logical,  but  extremely 
instructive  as  well. 

However,  since  the  bacteria  have  been  shown  to  have 
so  important  a  part  in  many  of  the  processes  intimately 
connected  with  health  and  disease,  it  will  doubtless  be 
advisable  to  devote  the  next  chapter  to  a  brief  review  of 
the  science  of  bacteriology.  This  done,  it  seems  to  the 
writer  that  we  shall,  as  beginners,  obtain  a  more  compre- 
hensive and  thorough  view  of  our  subject  if  we  pursue  a 
method  somewhat  as  follows  :  First,  to  discuss  air,  water, 
and  food — three  things  essential  to  life — in  the  varying 
conditions  and  circumstances  under  which  they  may  affect 
the  physical  welfare,  either  for  good  or  bad,  of  the  individ- 
ual or  of  the  community.  Then  to  take  up,  in  such  order 
as  may  seem  best,  the  other  themes,  such  as  climatology, 
habitations,  disinfection  and  quarantine,  disposal  of  sew- 
age, clothing,  exercise,  school  hygiene,  etc.,  whose  consid- 
eration, on  account  of  their  influence  in  the  pre-servation 
of  health  and  prevention  of  disease,  is  only  a  degree  less 


DUTY  OF  PHYSICIANS.  27 

important  than  the  foregoing.  In  this  way,  while  the 
whole  gronnd  may  not  be  covered,  the  importance  of  the 
various  subdivisions  may  be  estimated  in  their  relation- 
ship to  one  another,  and  we  shall  be  the  better  prepared 
to  pursue  the  study  as  opportunity  may  offer. 

It  is  doubtless  in  place  just  here  to  review  briefly  the 
reasons  why  it  is  the  special  duty  of  the  physician  to  be 
able  to  recognize  and  correct  insanitary  conditions  where- 
ever  they  may  be  found,  and  why  he  should  make  par- 
ticular and  constant  study  of  the  science  in  all  its  branches 
and  developments. 

Every  true  physician  soon  finds  that  the  respect  and 
affection  of  his  patients  and  associates  are  worth  far  more 
than  mere  mercenary  gain,  and  that  his  highest  aim  should 
be  to  prevent  disease  rather  than  simply  to  cure  it ;  and, 
though  this  may  seem  to  militate  against  his  personal  in- 
terests, he  is  unworthy  the  name  of  physician  if  his  object 
and  purpose  be  solely  or  primarily  to  make  money.  How- 
ever, the  observer  quickly  learns  that  in  a  community 
kept  in  good  health  and  sanitary  condition  there  will 
always  be  more  or  less  need  of  a  doctor's  services  in 
spite  of  every  effort  to  prevent  sickness,  and  that  such  a 
community  will  pay  more  promptly  and  more  liberally 
for  such  services  than  one  in  which  sanitary  precau- 
tions are  neglected.  Health  means  ability  to  work  and 
to  earn  good  wages ;  and  a  healthy  community  means 
more  business,  more  money,  and  more  comforts.  More- 
over, as  a  rule,  good  wages  insure  prompt  and  willing 
payment  of  the  doctor's  bills  as  well  as  of  others.  We 
may  note  here  the  close  relations  existing  between  sanitary 
science  and  social  and  political  economy — a  relationship 
which  is  very  intimate,  as  we  shall  see  from  time  to  time 
in  our  work,  for  as  the  physical  condition  of  a  people  is 


28  INTRODUCTION. 

bettered,  it  becomes  more  possible  and  more  certain  that 
they  will  likewise  improve  both  mentally  and  morally. 

Again,  though  the  science  of  hygiene  and  sanitation  is 
comparatively  a  new  one,  public  attention  is  being  strongly 
directed  toward  it,  not  only  because  it  vitally  interests 
every  one,  but  because  new  discoveries  and  new  appli- 
cations of  the  laws  pertaining  to  it  are  being  constantly 
made,  which  are,  in  turn,  swiftly  given  to  the  world  by 
both  the  scientific  and  the  popular  press.  This  creates  a 
demand  for  first-class  teachers,  which  demand  is  bound 
to  increase  in  the  near  future  and  promises  materially 
to  exceed  the  supply.  In  fact,  within  a  very  few  years 
not  only  the  medical,  but  also  the  academic  and  scientific 
colleges  of  the  country  will  be  compelled  by  public  opin- 
ion to  establish  in  their  faculties  well-equipped  and  liber- 
ally endowed  chairs  of  hygiene  and  sanitary  science,  and 
it  will  be  from  the  ranks  of  the  educated  pliysicians  of  the 
country  that  these  teachers  must  naturally  come.  It  will 
not  be  long  before  the  people  in  general  realize  that  it  is 
fully  as  important  that  the  college  student  or  graduate  be 
instructed  how  to  do  his  part  in  taking  care  of  the  health 
of  himself,  his  future  family,  and  the  community  in  which 
he  is  to  reside,  as  that  he  shall  be  well  taught  in  the 
abstract  principles  of  theology  or  the  classics  of  dead 
languages. 

So,  also,  considerably  more  time  and  attention  than  are 
now  accorded  to  it  should  l)e  given  to  hygiene  in  the  work 
of  the  various  normal  scliools  for  teachers.  The  graduates 
of  these  schools  will  have  much  of  the  physical  as  well  as 
the  mental  welfare  of  thousands  of  young  and  growing 
children  in  their  keeping,  and  it  is  unquestionably  their 
duty  to  prevent  or  obviate  the  ills  of  school-life  as  far 
as  lies  in  their  power,  and  to  give  instruction  in  and  to 


DEFINITION  OF  HEALTH  AND  DISEASE.  29 

iiKuilcatc  habits  of  living  which  will  continually  tend  to 
prescn've  and  improve  the  physical  health  of  those  under 
their  care. 

There  is  also  need  for  trained  sanitarians  in  the  service 
of  the  various  States  and  the  large  municipalities,  and 
there  is  now  an  actual  demand  for  such  men  with  no 
corresponding  supply  in  view. 

Lastly,  the  time  has  come  when  a  physician  must  neces- 
sarily have  a  knowledge  of  hygiene,  preventive  medicine, 
and  sanitary  science.  Many  States  require  as  thorough 
examinations  in  this  as  in  any  other  branch  of  medicine 
before  granting  the  right  to  practise  within  their  boun- 
daries. So  do  the  army,  navy,  and  marine-hospital  ser- 
vices of  the  government.  Moreover,  the  people  generally, 
as  has  been  intimated,  are  awakening  to  an  interest  in 
sanitary  matters  and  the  prevention  of  disease,  and  ex- 
pect their  physicians  to  be  well  versed  on  all  pertaining 
subjects ;  if  they  find  one  lacking  in  knowledge  or  interest 
in  this  respect,  they  are  apt  to  think,  rightly  or  wrongly, 
that  he  will  also  be  deficient  in  the  other  branches  of 
medicine. 

Happily  these  causes  all  combine  to  place  preventive 
on  the  same  high  plane  with  curative  medicine,  and  the 
time  is  fast  passing  in  which  the  chair  of  hygiene  fails 
to  have  a  primary  place  in  any  thorough  medical  school. 
May  the  day  soon  come  when  it  shall  have  at  least  equal 
importance  in  the  curriculum  of  all  academic  and  normal 
colleges  and  schools  ! 

It  is  evident  that  the  successful  physician  and  practical 
student  of  hygiene  must  have  a  thorough  knowledge  of 
three  things:  1.  Health  and  its  laws;  how  to  obtain  and 
preserve  it.  This,  of  course,  implies  a  knowledge  of  the 
human  body  and  its   functions,  viz.,  of  anatomy,  physi- 


30  INTR  OD  UCTION. 

ology,  and  physiological  chemistry.  2.  He  must  study 
disease  and  its  causes  and  nature.  He  must  also  under- 
stand the  distinction  between  diseases  due  to  causes  exter- 
nal and  those  due  to  causes  internal  to  the  body  ;  and  that 
while  some  of  these  causes  may  be  prevented  or  modified, 
others,  with  our  present  knowledge,  may  not  be  so  readily 
overcome.  3,  He  must  be  conversant  with  and  know  how 
to  use  the  therapeutic  agents,  both  preventive  and  cura- 
tive, that  he  has  at  his  disposal,  including  not  only  drugs, 
but  also  all  substances  and  forces  that  he  can  make  effica- 
cious to  his  purpose.  The  workman  must  know  his  tools 
to  be  able  to  use  them  intelligently. 

Health  is  "  that  condition  of  the  body  and  its  organs 
necessary  to  the  proper  performance  of  their  normal 
functions  "  ;  and  disease  may  be  defined  as  "  a  condition 
of  the  body  marked  by  inharmonious  action  of  one  or 
more  of  the  various  tissues  or  organs,  owing  to  abnormal 
condition  or  structural  change."  It  is,  accordingly,  well 
to  consider  briefly  the  nature  and  causes  of  disease,  that 
we  may  the  better  understand  the  influence  upon  its  pre- 
vention or  production  of  all  those  varying  factors,  phases, 
and  conditions  of  our  environment  which  we  hope  to 
study  in  our  work. 

Disease  is  a  pathologic  or  abnormal  physiologic  state, 
not  a  spiritual  thing ;  a  condition,  not  a  theory.  Conse- 
quently it  is  to  be  fought  and,  if  possible,  conquered  with 
matter,  force,  and  physical  means,  though  not  necessarily 
with  violence.  In  fact,  when  once  we  understand  the  min- 
uteness and  delicate  structure  of  the  ultimate  cells  and  tis- 
sues aifected,  we  realize  that  oftentimes  the  gentlest  a})plica- 
tion  of  the  forces  and  means  employed  may  be  the  most  help- 
ful aii<l  effieient.  But  when  one  lias  seen  the  ravages  caused 
by  it,  as  revealed  in  the  patliologieal  laboratory  and  at 


CLASSES  OF  DISEASE.  31 

autopsies,  not  to  speak  of  its  manifestations  in  the  living 
as  seen  in  the  sick-room  and  in  hospitals,  I  am  sure  that  he 
cannot  logically,  even  for  a  moment,  give  credence  to  those 
who  proclaim  that  it  can  be  dissipated  by  the  mere  action 
of  mind  or  of  faith  ;  nor  to  those  others  who  declare  that 
by  subdividing  and  diluting  and  subdividing  again  infini- 
tesimally  a  single  grain  of  substance,  whether  primarily 
powerful  or  inert,  you  endow  it  with  a  miraculous  power 
to  remove  the  "  ills  that  flesh  is  heir  to,"  Virchow  gave 
a  priceless  boon  to  modern  medicine  in  his  theory  of 
cellular  pathology  and  in  showing  its  superiority  to  the 
old  humoral  theories  and  a  priori  reasoning.  He  wrote 
"  whatever  outside  of  a  cell  acts  upon  it  (abnormally) 
works  a  mechanical  or  chemical  change  within  it,  which 
change  is  disorder  or  disease."  The  sooner  we  realize 
that  the  laws  of  physics  and  chemistry  govern  cell  life 
and  action  and,  consequently,  the  functions  and  organs  of 
the  body,  the  more  accurate  will  be  the  treatment  and 
the  more  certain  the  prevention  of  disease. 

For  convenience'  sake,  diseases  may  be  divided  into  two 
main  classes,  somewhat  different  in  their  origin,  nature, 
and  character,  although  the  line  between  the  two  is  not 
always  clearly  marked.  Diseases  of  the  first  class  arise 
within  the  body,  and  may  be  called  autogenetic.  They 
are  usually  due  to  some  alteration  or  disturbance  of  nu- 
trition and  assimilation,  such  as  irregular  absorption  of 
products  of  digestion,  or  of  function,  such  as  that  of  elimi- 
nation, to  either  of  which,  as  well  as  to  other  similar 
causes,  various  auto-intoxications  may  be  due.  The  sec- 
ond class  comprises  those  which  are  due  to  causes  from 
without,  favored,  it  may  be,  by  either  internal  or  external 
predisposing  conditions,  but  each  malady  of  necessity 
depending  upon  the  reception  or  inoculation  of  the  sjje- 


3  2  IN  TROD  UCTION. 

cial  cause,  which  cause  lias  the  power  of  reproduction  and 
development,  of  vitality  and  virulence.  Such  diseases 
are  called  contagious,  infectious,  specific,  inoculable,  or 
zymotic^ 

A  third  class  or  a  subdivision  might  also  be  indicated, 
Avhicli  would  include  those  disturbances  which  are  almost 
purely  psychical  and  whose  symptoms  are  largely  notional 
and  the  result  of  perverted  imagination  or  coordination. 
But  it  is  a  question  whether  the  primary  cause  of  almost 
all  such  disorders  is  not  an  altered  and  abnormal  nutri- 
tion or  functioning  of  the  general  nervous  economy  of 
the  body,  and  the  symptoms  simply  reflex  manifestations 
of  irritative  disturbances  of  distant  organs. 

In  the  first  class,  with  our  present  knowledge,  we 
may  place  such  maladies  as  rheumatism,  gout,  diabetes, 
neurasthenia,  etc.;  while  into  the  second  will  obviously 
fall  all  that  are  now  known  to  be  due  to  living  "  germs  " 
or  organisms,  such  as  cholera,  typhoid  fever,  malaria,  etc. 
However,  we  must  not  overlook  the  impulses  often  given 
to  the  causation  of  certain  members  of  the  second  class 
by  faulty  conditions  of  nutrition  or  assimilation,  as  is 
especially  exemplified  in  many  cases  of  tuberculosis. 
The  character  of  the  soil  may  influence  the  growth  and 

*  In  this  connection  the  following  quotation  from  Sedgwick  is  inter- 
esting: "  Diseases  may  be  regarded  as  due  either  to  defects  in  the  con- 
stitution or  construction  of  the  vital  mechanism,  or  else  to  external 
unfavorable  influences  acting  upon  it.  From  the  point  of  view  of  origin 
or  causation,  all  diseases  may  be  divided  into  two  classes,  viz. :  I.  Consti- 
tutional, or  II.  Enviroiunental.  This  classification,  while  open  to  many 
oiyections,  is  of  the  highest  value  to  the  physiologist  and  the  sanitarian, 
for  it  brings  the  former  face  to  face  with  intrinsic,  structural,  or  organic 
defects  in  the  mechanism,  while  the  attention  of  the  latter  is  concen- 
trated upon  those  abnormal  external  influences  which  act  unfavorably 
upon  the  organism,  and  which  he  must  seek,  and  may  be  able  to  re- 
move."— Principles  of  Sanitary  Science  and  Public  Health,  1902,  p.  10. 


PROPHYLAXIS.  33 

product  of  a  plant  almost  as  much  as  the  species  itself, 
and  so  the  difference  in  constitution  and  tissue  of  individ- 
uals may  materially  determine  the  variation  in  symptoms 
and  virulence  so  often  manifested  by  an  infectious  malady. 

Prophylaxis  is  "  the  use  of  hygienic  or  other  precau- 
tions conducive  to  the  prevention  of  disease "  ;  or  it  may 
be  defined  as  "  a  series  of  methods  or  procedures  whereby 
disease  is  restricted  and  prevented  by  suppressing  or  re- 
moving its  predisposing  conditions,  and  destroying  or 
modifying  the  exciting  causes."  Its  first  function  of  sup- 
pressing or  removing  predisposing  conditions  is  accom- 
plished by  sanitation;  the  second,  that  of  destroying  or 
modifying  exciting  causes,  is  carried  out  by  disinfection. 
The  term  "  predisposing  conditions "  should  be  used  in- 
stead of  "  predisposing  causes,"  because  these  conditions 
cannot  in  themselves  originate  a  disease,  though  they  may 
make  the  system  more  susceptible  to  the  exciting  causes 
of  a  disease.  For  example,  the  predisposing  factors  of 
tuberculosis — "privation,  depression,  and  excess" — are 
conditions,  and  though  they  often  prepare  the  tissues  for 
the  development  of  the  malady,  it  can  only  occur  after 
infection  by  the  exciting  cause,  viz.,  the  specific  tubercle 
bacillus. 

As  we  have,  as  yet,  little  definite  knowledge  of  the 
exact  nature  of  the  exciting  causes  of  autogenetic  diseases, 
they-  being  developed  and  elaborated  within  the  body, 
and  as  disinfection,  or  the  destruction  and  modification 
of  exciting  causes,  is  an  important  feature  of  prophylaxis, 
we  at  present  naturally  look  for  more  immediate  and 
satisfactory  results  in  the  application  of  prophylaxis  to 
the  second  class  of  diseases ;  but  this  does  not  prevent  or 
restrict  the  employment  of  certain  prophylactic  measures 
in  regard  to  the  first  class,  such  as  the  selection  of  proper 
3 


34  INTRODUCTION. 

diet,  clothing,  climate,  etc.,  and  the  removal  or  counter- 
acting of  all  influences  favoring  malnutrition  or  imperfect 
and  improper  functional  activity.  We  may,  therefore, 
say  that  sanitation  is  the  defensive,  disinfection  the  ag- 
gressive part  of  prophylaxis. 

To  suppress  and  remove  predisposing  conditions  and  to 
prepare  the  body  to  resist  and  repel  the  action  of  exciting 
causes,  we  must  not  only  strengthen  its  powers  of  resist- 
ance, but  also  make  all  external  media  as  favorable  to 
health  and  as  hostile  to  the  exciting  causes  as  possible. 
The  defensive  powers  of  the  body  must  lie  in  the  indi- 
vidual cells  and  tissues  of  the  body,  including  the  vital 
fluids,  and  it  is  but  natural  to  suppose  that  this  repellent 
action  to  noxious  substances  is  performed  best  when  the 
cells  and  tissues  are  in  most  perfect  health  and  most 
vigorous  condition.  This  is  not  only  good  logic,  but  all 
experience  and  scientific  research  go  to  show  that  it  has  a 
firm  foundation  in  fact. 

We  shall  soon  learn  that  purity  of  the  external  media 
and  environment  of  the  body  is  essential  to  its  welfare 
and  that  of  its  component  tissues,  and  that  conditions  of 
impurity  in  these  media  predispose  to  disease.  We  shall 
also  learn  that  a  proper  and  sufficient  supply  of  whole- 
some food  is  essential  to  health,  and  that  certain  other 
factors,  as  sex,  age,  clothing,  climate,  etc.,  may  act  for 
good  or  ill  in  the  determination  of  the  balance  between 
health  and  disease.  In  other  words,  if  we  strengthen  the 
resistant  powers  of  the  system  to  the  fullest  extent  and  re- 
move all  predisposing  conditions,  in  all  probability  the 
exciting  causes  will  be  inoperative  in  most  cases,  and  there 
will  b(!  no  iiuuirrence  of  disease.  This  is  the  essence  of 
sanitation  :  to  secure  perfect  health,  to  increase  the  inher- 
ent power  to  resist  noxious  and   harmful   influences,  and 


PROPHYLAXIS.  35 

to  make  all  the  surroundings  and  environments  of  the 
body  safe  and  free  from  depressant  factors.  This  applies 
equally  to  both  classes  of  disease ;  for  with  healthy  cells 
and  proper  food  there  will  not  be  faulty  nutrition  and 
assimilation  or  improper  functioning  and  the  consequent 
production  of  the  exciting  causes  of  autogenetic  disease ; 
and  with  a  vigorous  resistance  and  wholesome  environment 
there  is  little  opportunity  for  the  germs  of  infectious  mala- 
dies to  obtain  a  foothold  within  the  system  long  enough  to 
reproduce  themselves  and  cause  their  characteristic  dis- 
orders. The  best  means,  therefore,  of  preventing  disease 
is  to  learn  and  apply  the  best  methods  of  attaining  and 
retaining  a  healthy  and  vigorous  state  of  the  system,  viz., 
to  determine  and  observe  the  laws  of  hygiene. 


CHAPTER  II. 

BACTEEIOLOGY. 

The  increase  in  the  knowledge  concerning  the  lowest 
forms  of  life,  and  the  discovery  within  recent  years  that 
these  often  have  a  causative  action  in  the  excitation  of 
many  maladies,  have  greatly  facilitated  the  study  of 
the  prevention  of  disease.  In  fact,  it  is  largely  to  this 
advance  in  knowleds^e  and  to  the  confirmation  of  the  fferm 
theory  that  much  of  the  success  of  modern  hygiene  and 
sanitation  is  due.  In  addition  many  species  of  bacteria 
and  other  micro-organisms  are  of  extreme  importance  be- 
cause their  function  is  that  of  scavengers,  continually 
working  to  remove  and  convert  the  useless  and  harmful 
wastes  of  the  world  into  matters  of  high  value  as  food 
for  organic  life ;  while  still  other  kinds  are  being  found 
to  have  great  value  in  many  strictly  commercial  processes. 
A  review  of  the  chief  facts  concerning  them  will  there- 
fore be  in  place  at  this  time. 

The  unicellular  vegetal  micro-organisms  divide  them- 
selves into  two  general  classes  with  respect  to  their  man- 
ner of  reproduction,  viz.,  those  that  multiply  by  budding 
— the  blastomycetes — and  those  that  increase  by  simple 
division  or  fission — the  schizomyccfcs.  In  the  first  class 
we  have  the  hyphomycetes  or  mould-fungi,  and  the  sac- 
cliaromycetes  or  yeasts,  examples  of  these  being  fiimiliar 
to  every  one.  However,  it  is  with  the  fission-fungi,  or 
bacteria  as  they  are  now  more  generally  known,  that  we 
are  most  concerned  as  sanitarians,  since  they  practically 
include  almost  all  those  vegetal  micro-organisms  that  are 

36 


CHARACTERISTICS  OF  BACTERIA.  37 

more  or  less  closely  connected  with  the  production  of 
disease  as  well  as  with  the  removal  of  offensive  matter. 
Comparatively  few  of  the  yeasts  and  moulds  are  patho- 
genic, and  then  only  indirectly  or  in  a  minor  degree. 

Bacteriology,  then,  is  the  science  of  those  unicellular 
vegetal  micro-organisms  that  multiply  by  direct  division 
(fission),  or,  as  occasionally  happens,  by  the  development 
of  spores.  Its  study  consists  in  the  examination  by  means 
of  the  microscope  of  the  form  and  method  of  growth  of 
these  minute  plants,  in  their  artificial  cultivation  on  or  in 
suitable  media,  and  in  the  determination  of  the  effects  of 
the  inoculation  of  pure  cultures  upon  animals.  To  these 
may  be  added  another  field  of  research  that  gives  promise 
of  much  development  in  the  near  future,  viz.,  the  study 
of  the  chemistry  of  the  bacterial  products  and  of  the  reac- 
tions produced  by  their  presence  in  culture-media  and  in 
living  tissues. 

Although  more  than  two  centuries'  have  elapsed  since 
the  discovery  of  the  bacteria  by  Leeuwenhoek  (about 
1680),  and  though  Plenciz  advanced  as  early  as  1762 
what  is  practically  the  germ  theory  of  to-day,  mo^  of  our 
knowledge  concerning  the  physiology,  methods  of  cultiva- 
tion, and  differentiation  of  the  bacteria  has  been  acquired 
within  little  more  than  twenty  years.  It  is  true  that  some 
earlier  advance  had  been  made  in  sterilization,  and  that 
Cohn,  by  establishing  the  fact  of  spore-formation,  demol- 
ished the  last  arguments  in  favor  of  spontaneous  genera- 
tion, and  confirmed  the  science  of  bacteriology ;  but  until 
the  years  just  preceding  the  last  two  or  three  decades  we 
had  but  little  knowledge  as  to  the  means  of  separating 
and  isolating  the  different  species  and  making  pure  cul- 
tures, or  of  preparing  culture-media,  staining,  etc. 

As    has  l)een    intimated,  the   bacteria   are    unicellular 


38 


BACTERIOLOOY. 


organisms,  usually  multiplying  by  a  process  of  cell-elonga- 
tion and  fission.  Being  without  chlorophyll,  they  cannot 
absorb  and  decompose  carbon  dioxide  and  ammonia,  as  do 
the  higher  plants  ;  but  require  for  their  growth  and  nutri- 
tion organic  matter — usually  soluble  albumin — in  the  pres- 
ence of  moisture.^  Hence  they  must  be  either  saprophytes 
or  parasites.     As  the  combination  of  albuminous  organic 


Micrococfi  (gonococcij  in  jju.s-cells.     X  1000. 

matter  and  water  is  extremely  common,  so  the  distribu- 
tion of  the  bacteria  over  the  earth  is  widespread  and  })rac- 
tically  universal. 

Some  of  the  bacteria  may,  under  adverse  conditions, 
such  as  lack  of  nutriment  or  of  moisture,  too  alkaline  or 
ttio  acid  a  medium,  extremes  of  temperature,  etc.,  or  on  the 
other  hand,  as  a  result  of  the  attainment  of  a  stage  of 

'  It  will  be  understoofl  that  these  statements  and  many  of  those  to 
follow  are  more  or  less  ;;eneral,  and  that  certain  species  of  the  bacteria 
may  present  notable  exceptions. 


CHARACTERISTICS  OF  BACTERIA.  39 

maximum  development,  produce  spores  which  are  much 
more  strongly  resistant  to  deleterious  influences  than  the 
bacteria  themselves.  In  this  way  the  spore-forming 
species  may  often  survive  the  action  of  disinfectants  or 
other  agencies  that  are  sufficient  to  destroy  other  bacteria. 
Upon  the  resumption  or  recurrence  of  favorable  conditions 
the  spores  develop  into  cells  similar  in  form  and  nature 
to  their  parent  cells.     It  is  to  be  remembered  that  spores 


1 


'       \^     \ 


Tubercle  bacilli  in  sputum.    X  1000. 

do  not  reproduce  spores,  and  that  "  a  single  cell  produces 
but  one  spore."  ^ 

Under  the  microscope  the  spores  are  seen  as  highly 
refractive  spherical  bodies  that  stain  with  difficulty,  and 
evidently  have  a  very  resistant  envelope,  probably  of  cellu- 
lose. The  interior  of  bacteria  and  spores  is  protoplasm. 
So  far  as  is  positively  known  at  this  time,  only  certain  of 
the  bacilli  form  spores,  while  a  few  of  the  spirilla  and 
1  Abbott,  Principles  of  Bacteriology,  1st  ed.,  p.  31. 


40  BACTERIOLOG  Y. 

one  or  two  species  of  micrococci  probably  have  the  same 
faculty. 

Again,  under  certain  peculiar  conditions  some  organisms 
may  develop  another  morphologic  change,  the  so-called 
involution-forms.  These  are  doubtless  pathologically 
distorted  cells,  with  probably  diminished  resisting  powers, 
but  which  will  revert  to  the  normal  type  under  favorable 
conditions,  providing  the  unfavorable  environment  does 
not  kill  them. 

Lastly,  at  times  certain  individuals  of  a  species  seem  to 
have  departed  from  the  typical  form,  but  these  departures 
are  only  diflFerent  phases  in  the  normal  development.  Thus 
a  young  bacillus  may  be  shorter  than  the  adult  and  look 
much  like  a  coccus,  or  a  coccus  about  to  undergo  division 
may  be  oval  in  shape  and  considerably  larger  than  the 
quiescent  members  of  its  species.  But  one  form  of 
bacteria  never  permanently  takes  that  of  another — micro- 
cocci are  always  micrococci,  bacilli  always  bacilli,  etc. 

A  thoroughly  scientific  classification  of  the  bacteria  is 
scarcely  possible  as  yet,  owing  to  our  incomplete  knowl- 
edge of  their  character,  method  of  growth,  physiology, 
etp.  However,  there  are  a  number  of  ways  in  which  we 
may  subdivide  them,  none  of  them  exactly  scientific,  per- 
haps, but  still  sufficiently  accurate  and  convenient  for 
our  purpose.  If  we  consider  the  bacteria  as  to  form,  we 
have  :  (a)  micrococci,  spherical  in  shape  ;  (6)  bacilli,  which 
have  one  diameter  longer  than  another;  and  (c)  spirilla, 
spirals  or  segment  of  spirals.'  AVe  shall  have  more  to  say 
hereafter  of  the  characteristics  of  each  of  these  subdivisions, 

'  Af-curately  speaking,  some  of  the  so-called  higher  bacteria  have 
more  elaborate  development  and  distinction  as  to  form,  but  as  our  pres- 
ent discussion  has  almost  entirely  to  do  with  the  phenomena  of  the  lower 
and  simpler  bacteria,  the  former  may  henceforth  be  omitted  from  the 
discussion. 


CLASSTFICATION  OF  BACTERIA.  41 

Accordingly  as  they  live  best  with  or  without  air  or  oxy- 
gen they  are  aerobic  or  anaerobic.  Again,  they  may  be 
named  according  to  their  product — e.  g.,  some  produce 
colors,  chromogenic ;  others  pus,  pyogenic,  etc.  Lastly, 
they  exist  and  grow  either  as  saprojihytes  upon  dead,  or 
as  parasites  upon  living  organic  matter.  We  also  say 
that  an  organism  is  opdional  or  facultative  when  it  is  at 
one  time  a  saprophyte  and  at  another  a  parasite,  or  at 
one  time  aerobic  and  again  anaerobic ;  and  that  it  is 
obligate  when  it  has  not  this  property  of  changing  its 
nature  according  to  surrounding  conditions. 

Some  of  the  micrococci  are  named  according  to  the 
manner  in  which  they  grow.  If  in  pairs,  they  are  called 
d ijjlo cocci ;  in  fours,  tetracocci ;  in  threads,  streptococci, 
etc.  Groups  or  masses  of  micrococci  or  bacilli  held  to- 
gether by  a  gelatinous  substance  are  called  zobglea.  As 
compared  with  other  bacteria,  with  one  or  two  exceptions, 
we  know  but  little  about  the  spirilla.  The  germ  of 
cholera — the  comma  bacillus  (?) — belongs  to  this  class, 
and  the  cause  of  relapsing  fever  is  also  probably  a  spirillum. 

Most  of  the  bacteria  thrive  best  in  culture-media  that 
are  neutral  or  only  slightly  alkaline,  though  a  few  species 
seem  to  do  better  in  slightly  acid  surroundings.  So,  also, 
they  do  best  at  temperatures  ranging  between  20°  and 
40°  C.  (68°  and  104°  F.),  though  they  may  grow  at  any 
temperature  between  5°  and  43°  C.  (41°  and  109.4°  F.). 
Any  marked  deviation  in  the  culture-media  from  the 
neutral  point  or  continued  exposure  to  extremes  of  tem- 
perature may  either  check  the  growth  of  the  organisms 
altogether,  and  eventually  destroy  them,  or  may  cause 
spore-formation,  or  the  production  of  involution-forms, 
or  a  change  in  the  composition  and  the  character  of  the 
chemical  products  which   the   l)acteria  normally  produce. 


42  BACTERIOLOGY. 

This  also  holds  good  with  respect  to  any  other  condition  or 
substance  that  may  be  deleterious  to  the  bacteria  in  their 
normal  state ;  wherefore  we  shall  see  that  such  factors  are 
important  as  having  a  decided  influence  in  altering  the  viru- 
lence of  pathogenic  bacteria  and  in  suggesting  methods  for 
bringing  about  a  condition  of  immunity  to  their  attaclcs. 

As  it  is  rare  to  find  isolated  individual  species  anywhere 
except  in  pure  cultures  artificially  prepared,  it  is  evident 


Spirillum  of  Asiatic  cholera.    X  1000. 

that  wc  must  devise  some  way  of  separating  the  different 
kinds  of  organisms  one  from  another.  This  is  best 
accom})lished  by  the  method  suggested  by  Koch,  viz.,  to 
introduce  the  mixed  kinds  into  some  melted  culture- 
medium,  like  nutrient  gelatin,  which  .solidifies  on  cooling, 
but  who.se  melting-point  is  not  sufficiently  high  to  destroy 
the  vitality  of  the  germs.  If  the  fluid  be  well  shaken, 
the  various  species  will  be  distributed  through  it,  and,  upon 
cooling,  each  individual  or  group  (zooglea)  of  individuals 


SEPARATION  OF  SPECIES. 


43 


of  the  same  kind  will  be  fixed  in  its  place  and  become  the 
starting-point  of  a  colony  of  that  special  kind.  Moreover, 
if  the  gelatin    before  cooling  be  poured    upon  sterilized 

Fig.  4. 


Bacilli  of  hog  cholera,  showing  flagella.    X  1000. 

glass  plates  or  into  flat  (Petri)  dishes  (Fig.  5),  the  subse- 
(pient  work  of  counting,  examining,  and  making  cultures 
from  the  colonies  thus  secured  will  be  greatly  facilitated, 

Fig.  5. 


Petri  double  dish  (now  generally  used  instead  of  plates). 

while  by  transplanting  and  repeating  the  process  one  or 
more  times,  absolutely  pure  cultures  of  each  species  in 
the  original  mixture  may  be  obtained. 


44  BA  CTERIOL  0  G  Y. 

Special  care  must  be  taken  in  this,  as  in  all  other  bacte- 
riological methods  or  operations,  to  prevent  contamination 
of  cultures,  media,  or  apparatus  by  other  organisms  which 
are  almost  omnipresent,  and  which  would  prevent  accurate 
results  or  deductions  were  they  not  rigidly  excluded  or 
destroyed.  Obviously,  we  may  not  use  chemical  disinfect- 
ants or  antiseptics  as  a  means  of  destroying  the  interfering 
microbes,  for  such  procedure  would  kill  or  inhibit  the 
growth  of  the  bacteria  w^e  desire  to  cultivate ;  but  we  must 
sterilize  by  heat  all  the  articles  used,  together  with  their 
contents.  This,  if  properly  done,  does  not  affect  the 
nutrient  properties  of  the  culture-media,  while  it  does 
remove  the  danger  of  contamination  already  present. 

In  sterilizing  we  may  use  either  dry  or  moist  heat,  the 
latter  being  far  more  preferable  in  most  cases,  since  to 
be  effectual  it  does  not  require  so  high  a  temperature  nor 
^so  long  a  time  as  does  the  former.  Moist  heat,  especially 
in  the  form  of  steam,  is  more  penetrating  than  dry  heat ; 
beside,  dry  heat  must  be  of  so  high  a  temperature  that 
it  may  render  useless  for  culture  purposes  such  substances 
as  nutrient  gelatin.  Glassware  and  the  like,  however, 
may  be  quickly  and  advantageously  sterilized  by  dry  heat. 
On  tlie  other  hand,  certain  substances,  like  blood-serum, 
are  spoiled  for  culture  purposes  even  by  moist  heat  con- 
tinued sufficiently  long  to  kill  the  spores  possibly  present, 
as  the  latter  require  a  higher  temperature  or  more  pro- 
longed heatintr  to  sterilize  them  than  the  bacteria  without 
spores.  Resort  is  therefore  had  U)  /racfional  KierUkdtion  in 
such  cases,  exposing  tlie  materials  for  only  a  short  time  to 
a  temperature  just  sufficient  to  destroy  tlie  bacteria,  repeat- 
ing tlie  process  after  an  interval,  say  twenty-four  hours, 
which  is  presumably  sufficient  to  allow  the  spores  to 
develop  into  bacteria;  and  again  a  third  time,  after  a  like 


STERILIZATION. 


45 


interval,  to  insure  absolute  sterilization.  Previous  to 
sterilizing  the  culture-media  and  apparatus  w^e  aim  to  pre- 
vent the  subsequent  access  of  contaminating  germs  to  the 
interior  of  tubes  and  vessels  by  using  plugs  or  stoppers  of 
cotton-wool,  covering  these,  when  necessary,  with  rubber 
caps  or  paraffin  wax  to  prevent  the  evaporation  of  fluids 
or  of  moisture  from  the  gelatin,  etc. 

Fig.  6. 


steam  sterilizer,  pattern  of  Koch. 

As  a  basis  for  a  number  of  culture-media  we  may  use 
beef-broth  or  bouillon,  which  is  a  fluid  especially  favor- 
able to  bacterial  growth  in  that  it  contains  an  abundance 
of  albumin  in  solution.  When  a  solid  medium  is  desired, 
either  gelatin  or  agar-agar  (a  gelatin-like  substance  ob- 
tained from  Japan)  may  be  added  to  bouillon,  giving 
nutrient  gelatin    and   nutrient  agar-agar.     Of  these,   the 


46 


BACTERIOLOGY. 


gelatin  has  a  melting-point  below  the  temperature  of  the 
human  body,  while  that  of  agar  is  above ;  consequently  we 
employ  the  latter  when  it  is  desired  to  cultivate  germs  that 
grow  best  at  the  body  temperature,  although  the  develop- 
ment of  most  bacteria  is  usually  more  rapid  and  charac- 
teristic upon  gelatin.  Blood-serum,  sterilized  and  solidi- 
fied, is  also  used  for  the  cultivation  of  certain  organisms, 

Fig.  7. 


Arnold  steam  sterilizer. 


such  as  the  diphtheria  bacillus;  and  there  are  certain 
others  which  can  best  be  identified  by  their  difference  in 
growth  upon  boiled  potato,  milk,  etc. 

The  differentiation  of  the  various  species  of  bacteria  is 
to  be  made  by  noting  their  appearance  and  form  under 
the  microscope,  wliethcr  they  are  motile  or  not,  how  tliey 
take  different  stains,  etc. ;  by  observing  their  methods  of 
growth  in  or  upon  different  culture-media,  and  the  color 
and  appearance  of  the  colonics ;  by  noting  whether  tlujy 


DIFFERENTIATION  OF  SPECIES. 


47 


are  aerobic  or  anaerobic,  or  facultative,  and  at  what  tem- 
peratures they  tlirive  best,  etc. ;  and  finally  by  studying 
their  action  and  the  eiFect  of  their  products  upon  living 
animals.  In  this  way  we  may  determine  the  characteris- 
tics of  each  individual  or  species,  and  will  eventually  have 
the  data  for  a  strictly  scientific  classification  of  the  bac- 
teria in  general.  For  example,  the  organisms  causing 
suppuration  are  usually  micrococci,  occurring  in  clusters 
(staphylococci)  or  in  chains  (streptococci) ;  the  cause  of 
typhoid  fever  is  a  bacillus,  and  the  cholera  germ  belongs 
to  the  spirilla.     The  tubercle  bacillus  stains  with  marked 

Fig.  8. 


Ruled  square  for  counting  colonies. 


difficulty,  but  when  stained  is  not  readily  decolorized  by  a 
weak  solution  of  nitric  acid,  as  are  almost  all  other  bacilli. 
Some  bacteria  liquefy  nutrient  gelatin,  others  do  not,  and 
almost  none  liquefy  agar-agar.  This  liquefaction  is  not  a 
melting,  but  rather  a  probable  peptonization,  since  the 
gelatin  will  not  solidify  after  this  occurs,  as  it  does  after 
being  subjected  to  moderate  warming.  Again,  some  bac- 
teria produce  one  particular  color  or  chemical  substance  in 
the  presence  of  oxygen,  and  another  in  its  absence;  some 
j^roduce  color  only  in  the  light,  others  only  in  the  dark, 
etc.  Finally,  different  pathogenic  microbes  cause  differ- 
ent maladies  when  inoculated  in  animals  or  human  beings. 


48  BACTERIOLOGY. 

and  the  same  germ   may  produce  diiferent  results  in  ani- 
mals of  different  species  or  families.' 

The  subdivision  of  the  bacteria  into  saprophytes  and 
parasites  has  already  been  noted.  Therefore,  it  must  be 
remembered  that  not  all  of  these  microscopic  plants  are 
disease-producers;   much  the  larger  proportion,  in  fact, 

Fig.  9. 


Pocket-case  containing  sterilized  culture-tubes,  platinum  needle,  and 
alcohol  lamp,  used  for  obtaining  cultures  for  diagnosis,  etc. 

being  benefactors    rather   than    otherwise  to  the  human 
race. 

The  function  of  many  of  the   saprophytic  organisms 
is  to  change  dead  organic  matter   into  simpler  chemical 

1  See  Kenwood's  Hygienic  Laboratory,  pp.  466-470;  also  McFarland's 
Pathogenic  Bacteria,  pp.  46-.'J7. 


FUNCTIONS  OF  SAPROPHYTES.  49 

compounds  and  ultimately  into  end-products  such  as  carbon 
dioxide,  ammonia,  and  water,  these  latter  substances  being 
once  more  utilized  in  the  nutrition  of  the  higher  forms 
of  vegetable  life,  which  are  in  turn  necessary  to  the  exist- 
ence of  the  animal  life  upon  the  globe.  One  should  also 
understand  that  some  of  the  saprophytes  in  the  soil  seem 
to  possess  a  constructive  or  synthetic  power,  elaborating 
more  complex  plant-foods  from  the  simple  compounds  men- 
tioned. Indeed,  it  is  only  M^hen  the  student  of  hygiene 
fairly  realizes  the  wide  scope  of  the  functions  of  these  mi- 
nute but  almost  omnipresent  scavengers  that  he  will  com- 
prehend the  important  part  they  play  in  the  purification 
of  our  environment.  In  the  air  they  possibly  help  the 
oxygen  to  destroy  the  harmful  effluvia  and  exhalations  of 
men  and  animals  and  the  floating  debris  of  organic  sub- 
stances ;  in  the  soil,  the  common  receptacle  of  the  wastes 
and  refuse  of  vital  activity,  they  quickly  and  continually 
convert  these  noxious  additions  into  foods  of  the  highest 
value  to  growing  plants ;  in  running  streams  and  quiet 
pools  they  are  of  the  greatest  importance  in  the  removal 
of  the  dangerous  impurities  washed  from  the  surface  of 
the  land  or  recklessly  discharged  from  human  habitations, 
factories,  and  the  like.  And  not  only  do  the  saprophytes 
help  mankind  in  this  way,  but  members  of  the  class  are 
beneficent  in  many  others.  For  example,  they  enable 
those  plants,  the  leguminosse,  which  yield  us  the  largest 
supply  of  vegetable  proteids,  to  derive  much  of  their 
nitrogen  almost  directly  from  the  atmosphere ;  they  have 
much  to  do  with  the  flavor  and  value  of  dairy  products, 
and  uses  in  which  they  may  be  employed  in  the  domestic 
and  commercial  aifairs  of  life  are  being  newly  announced 
from  day  to  day.  Thus  we  find  the  bacteria  of  this  class, 
which  comprises  by  far  the  greater  number  of  known 
4 


50  BACTERIOLOGY. 

species,  to  be  our  benefactors  and  indispensable  servants 
both  in  preventing  the  accumulation  of  noxious  and  harm- 
ful substances  upon  the  earth  and  in  helping  to  produce 
the  food  which  we  eat  and  many  things  that  we  need  and 
use  in  our  daily  life. 

The  parasitic  bacteria,  on  the  other  hand,  have  their 
habitat  in  or  upon  highly  organized  living  matter,  and 
exist  at  its  expense.  They  also  produce  in  their  growth 
poisonous  substances,  called  toxins  and  toxalbiimins,  that 
are  either  locally  or  generally  harmful  to  the  organism 
that  is  their  host.  It  is  needless  to  say  that  it  is  in  this 
class  that  we  find  the  disease  germs,  or  pathogens  as  some 
would  call  them.  It  should  not  be  forgotten,  however,  that 
the  saprophytes,  in  bringing  about  the  decomposition  of 
complex  organic  bodies,  may  also  produce  jytomdins,  which 
may  or  may  not  be  toxic  to  animal  life.  Of  these  latter, 
we  may  instance  as  good  examples  the  cadaveric  poison  of 
the  dissecting-room  or  the  dangerous  tyrotoxicon,  a  by  no 
means  uncommon  product  in  the  decomposition  of  milk  or 
ice-cream.  But  though  ptomai'ns  may  be  more  or  less  char- 
acteristic of  the  respective  bacteria  that  produce  them,  each 
varies  in  its  composition  and  properties  according  to  the 
substance  upon  or  in  which  it  is  produced,  while  the  toxins 
are  specific  derivatives  or  "active  principles"  of  their 
respective  micro-organisms.  In  other  words,  different 
kinds  of  saprophytes  may  produce  the  same  ptomain 
from  a  given  organic  substance,  but  each  toxin  is  the 
product  of  its  own  particular  species  of  bacteria  and 
is  independent  of  tlie  hitter's  place  of  growth  or  environ- 
ment. 

Considering  for  tlic  present  the  pathogenic  bacteria 
alone,  we  are  naturally  brought  to  the  discussion  of  the 
f/rrm  fhrorij,  wliich    is,   that  the  exciting  cause   of  each 


TOXTNS  AND  PTOMAINS.  51 

contagious  or  infectious  disease  is  some  specific  parasitic 
organism,  and  that  these  diseases  are  each  communicated 
only  by  the  transference  to  and  development  of  its  par- 
ticular parasite  or  germ  within  or  upon  the  tissues  of  the 
infected  individual.  CConsequently  suchcHseases  aretrails^ 
mitted  from  one  person  to  another,  or  in  some  cases  from 
animals  to  men  or  vice  versa,  by  means  of  these  micro- 
organisms, and  the  transferrence  is  by  air,  water,  food,  or 
other  fomites,  or  by  direct  contact.  It  is  evident  that  if 
acquired  knowledge  establishes  the  truth  of  this  theory, 
the  prevention  of  infectious  diseases  is  greatly  simpli- 
fied and  becomes  merely  a  matter  of  combining  effective 
sanitation,  of  which  we  have  spoken,  with  the  destruction 
of  the  specific  exciting  causes — i.  e.,  disinfection.  Nor  is 
it  essential  that  we  any  longer  make  a  distinction  between 
the  terms  contagious,  infectious,  zymotic,  and  specific,  that 
formerly  obtained,  since  they  may  practically  be  used 
synonymously.  I'he  first  of  these  terms  used  to  be  ap- 
plied to  those  diseases  which  were  believed  to  be  trans- 
mitted most  frequently  by  direct  contact,  and  infectious 
to  those  of  which  the  transmission  was  usually  by  fomites. 
But  we  know  that  germs  of  the  former  class  may  be  trans- 
mitted by  air,  water,  food,  etc.,  and  those  of  the  latter  by 
personal  contact,  though  the  reverse  is  what  usually  hap- 
])ens  in  the  respective  cases.  Occasionally  disease  occurs 
also  by  inoculation,  the  exciting  organisms  being  intro- 
duced into  the  body  either  accidentally  or  intentionally 
through  some  wound  in  the  pr(itecting  skin  or  mucous 
membrane.  The  term  zymotic  was  formerly  applied  to 
those  diseases  occurring  in  ejjidemics,  and  which  were 
supposed  to  be  due  to  fermentative  processes ;  if  used  at 
all,  it  should  be  given  to  any  disease  due  to  a  living 
germ.     The  term  specific  should  only  be  given  to  those 


52  BACTERIOLOGY. 

maladies  which  have  a  specific  origin — i.  e.,  which  have 
been  proved  to  be  due  to  a  single  organism. 

In  this  connection  we  may  define  an  epidemie  as  "  an 
outbreak  of  a  communicable  or  infectious  disease  affecting 
a  dozen  or  more  individuals  in  quick  succession  before  the 
recovery  of  the  first  case,  whether  arising  from  a  single 
focus  or  several  foci  in  a  neighborhood."^  An  endemic 
disease  is  one  occurring  more  or  less  constantly  in  a  cer- 
tain locality.  When  an  epidemic  extends  over  a  very 
large  territory,  it  is  said  to  be  j^jandemic. 

That  all  communicable  diseases  are  due  to  vegetal  germs 
or  kindred  animal  organisms  is  more  than  probable,  and 
while  there  are  some  for  which  this  has  not  been  fully 
proved,  it  is  scarcely  possible  that  any  of  these  may  arise 
from  insanitary  conditions  without  the  presence  of  a  living 
causative  organism. 

The  reasons  for  believing  in  the  germ  theory  are  based 
on  empirical  and  logical  facts  as  well  as  theoretical  hypoth- 
eses. Ignoring  at  present  the  scientific  research  work 
already  done,  it  is  evident  that  the  substance  that  causes 
a  disease — the  contagium — must,  when  introduced  into  a 
susceptible  person  or  animal,  increase  in  quantity  to  an 
enormous  extent.  Note,  for  instance,  the  large  quantity 
of  actively  virulent  matter  thrown  off  from  a  case  of 
small})ox  or  scarlet  fever,  and  yet  how  very  little  is 
required  to  initiate  an  attack  of  the  disease.  No  inert 
chemical  substance  has  the  power  of  being  increased  to 
such  an  extent  by  simply  finding  lodgment  in  a  suitable 
medium.  The  poison  or  contagium,  whatever  it  may  be, 
evidently  must  have  life  and  the  power  of  reproduction. 

Moreover,  these  causes  of  disease,  when  freed  from  the 
body,  may  be  carried  long  distances,  and  may  still  retain 

'  Committee  of  American  I'liblic  Jlfiilth   Asaociatiou,  1898. 


KOCH'S  POSTULATES.  53 

for  years  their  power  for  harm,  only  waiting  a  suitable  field 
in  which  to  multiply  and  cause  the  same  malady  as  before. 
Such  causes  must  therefore  be  capable  of  entering  a  state 
in  which  vitality  is  latent,  and  in  which  the  reproductive 
functions  are  for  a  time  inactive.  But  it  is  known  that 
the  spores  of  many  bacteria,  and  sometimes  the  bacteria 
themselves,  may  be  carried  afar,  kept  for  long  periods  of 
time,  and  even  exposed  to  wide  extremes  of  temperature, 
without  being  killed  or  losing  their  power  of  reproduction 
and  rapid  multiplication.  Again,  we  know  that  substances 
that  are  poisonous  to  or  that  prevent  the  development  of 
these  bacteria  and  kindred  low  forms  of  life,  do,  when 
properly  used,  prevent  or  remove  the  danger  of  contagion 
and  infection. 

There  is  also  in  the  development  and  progress  of 
infectious  disease  a  direct  analogy  to  the  phenomena  of 
fermentation,  whose  causative  organisms  are  of  the  same 
order  as  these  which  we  are  considering ;  the  same  rapid 
multiplication  of  cells  in  suitable  media  at  proper  tem- 
peratures— a  period  of  incubation — and  then  changes  in  the 
infected  body  or  host,  which,  after  going  on  to  a  certain 
extent,  check  the  further  development  and  multiplication 
of  the  organism.  AVhat  it  is  in  the  medium  that  checks 
the  growth  of  the  germ  we  may  not  be  able  to  determine 
a  priori,  but  we  may  assume  it  to  be  something  hostile  to 
the  contagium,  as  alcohol  above  a  certain  percentage  in 
the  fermenting  medium  is  deterrent  to  the  further  growth 
of  the  yeast-cell. 

Lastly,  if  the  proof  of  Koch's  postulates  is  essential  to 
the  acceptance  of  a  given  micro-organism  as  the  cause  of 
a  given  disease,  we  must  believe,  on  the  other  hand,  that 
a  certain  germ  is  a  cause,  if  not  the  only  one,  of  a  certain 


54  SA  GTERIOLOG  Y. 

malady  if  these  postulates  be  proved  \vith  respect  to  the 
germ  and  the  malady. 

To  determine  whether  an  organism  is  or  is  not  patho- 
genic it  is  necessary  to  experiment  on  living  animals.  To 
do  this  we  must  use  pure  cultures  of  the  organism  and 
carry  out  all  our  processes,  including  inoculations  and 
autopsies,  under  strictly  antiseptic  precautions.  For  ex- 
ample, we  may  examine  microscopically  the  blood  and 
various  tissues  of  a  diseased  animal ;  if  bacteria  be  present 
in  any  of  these,  we  make  cultures  from  them,  and  if  more 
than  one  kind  of  bacteria  be  present,  the  various  kinds 
must  be  isolated  and  pure  cultures  made  from  each  kind. 
When  a  pure  culture  is  at  last  obtained,  it  may  be  studied 
both  microscopically  and  as  to  its  characteristics  in  various 
media  and  at  diiferent  temperatures.  Finally,  healthy 
animals  known  to  be  susceptible  to  the  disease  in  question 
are  inoculated  from  the  pure  culture  and,  after  the  period 
of  incubation,  carefully  watched  for  symptoms  of  the  dis- 
ease. Should  these  manifest  themselves,  the  animal  is 
killed  and  its  blood  and  tissues  carefully  examined  for 
the  inoculated  organisms.  A  similar  study  is  to  be  made 
of  each  species  isolated  from  the  first  animal. 

The  postulates  of  Koch,  which  are  necessary  to  prove 
that  a  germ  is  the  cause  of  a  given  disease,  are  :  1.  The 
micro-organism  must  be  found  in  the  blood,  lymph,  or 
tissues  of  a  person  or  animal  sick  or  dead  of  the  disease. 
2.  The  micro-organism  must  be  isolated  from  the  blood, 
lymph,  or  tissues,  and  cultivated  in  suitable  media  out- 
side of  the  animal  body.  These  cultivations  must  be 
carried  on  through  several  generations  until  a  pure  cult- 
ure of  the  germ  is  obtained.  3.  A  pure  culture  thus 
obtained  must,  when  introduced  into  a  healthy  and  sus- 
ceptible animal,  produce  the  disease  in  question.     4.  In 


KOCH'S  POSTULATES.  55 

the  inoculated  animal  the  same  organism  must  again  be 
found. 

In  the  case  of  many  diseases  peculiar  to  human  beings 
alone  the  third  condition  must  remain  undetermined  and 
our  chain  of  proof  be  broken,  because  we  should  not  en- 
danger human  health  or  life  by  experimental  inoculations. 
But  in  diseases  common  to  men  and  animals  the  experi- 
ments necessary  can  be  completely  carried  out,  and  where 
a  germ  can  be  proved  to  be  the  cause,  according  to  these 
postulates,  of  the  malady  in  animals,  we  can  also  fairly 
conclude  that  it  is  the  cause  of  the  same  disease  in  human 
beings.  The  specific  germs  of  a  number  of  maladies  com- 
mon to  man  and  beast  have  thus  been  determined,  together 
with  those  of  a  large  number  of  affections  peculiar  to  ani- 
mals alone. 

Granting  that  a  certain  organism  be  pathogenic,  infec- 
tion by  it  will  depend  not  only  upon  the  susceptibility  of 
the  animal  or  person  concerned,  but  also  upon  the  method 
of  entrance  into  the  body,  the  number  of  microbes  intro- 
duced and  present,  and  especially  upon  their  degree  of 
virulence.  Thus,  the  tubercle  bacilli  produce  effects  of 
different  character  and  gravity  in  different  tissues,  and  it 
needs  no  argument  to  show  that  while  the  normal  resistance 
of  the  body  may  be  all-sufficient  to  overcome  a  few  vicious 
germs  taken  in  with  the  air,  food,  or  drink,  it  may  be  en- 
tirely inadequate  to  resist  and  may  quickly  succumb  to 
large  numbers  of  the  same  enemy,  especially  if  the  viru- 
lence of  the  latter  be  enhanced,  as  we  now  know  it  may 
be,  by  various  factors  that  thus  assume  great  sanitary 
importance.  Not  the  least  of  these  are  temperature  and 
nutrient  conditions,  and  change  in  potency  due  to  growth 
and  development  in  certain  animal  or  human  bodies. 

After  infection  or  the  reception  of  the  contagium  by  a 


56  BACTERIOLOGY. 

susceptible  animal  or  person  there  is  a  period  of  incuhd- 
tion  before  the  manifestation  of  the  characteristic  symp- 
toms of  the  disease.  This  period  is  variable  according 
to  the  disease  or  kind  of  germ,  and  during  it  the  micro- 
organisms rapidly  increase  in  numbers  and  in  their  conse- 
quent power  for  evil. 

After  the  pathological  process  is  well  under  way  we 
shall  probably  find  one  of  two  conditions  existing,  viz., 
that  "  in  which  the  blood  is  the  chief  field  of  activity  of 
the  organisms,"  ^  and  the  vessels  of  the  victim  are  swarm- 
ing with  the  microbes — in  other  Avords,  a  true  septiccemia  ; 
or  else  one  in  which  "  the  poisonous  results  are  not  neces- 
sarily accompanied  by  the  growth  of  organisms  in  the 
tissues,"  these  latter,  in  all  likelihood,  not  extending 
beyond  the  lymphatic  glands  nearest  to  the  point  of  inocu- 
lation— i.  c,  a  toxcemia.  A  good  example  of  the  former 
condition  is  furnished  by  a  case  of  anthrax  or  of  pyaemia, 
and  of  the  latter  by  diphtheria.  However,  we  shall  find 
in  either  condition  that  if  we  isolate  the  peculiar  product 
or  toxin  of  the  specific  germ,  either  from  artificial  growths 
upon  or  in  culture-media,  or  from  the  blood  or  tissues  of 
an  animal  sick  or  dead  of  the  disease,  and  inoculate  this 
into  a  susceptible  animal,  the  general  symptoms  and 
results  produced  are  practically  the  same  as  in  an  ordinary 
case  of  the  disease.  This  goes  to  prove  that  the  products 
of  pathogenic  bacteria  are  toxic  in  character  and  harm- 
ful to  the  tissues,  either  locally  or  generally  ;  that  each 
of  these  toxic  products  gives  rise  in  susceptible  animals  to 
characteristic  symptoms  which,  taken  together,  indicate 
a  s])ecific  disease,  and  that  infection  must  be  accordingly 
a  biochemic  and  toxicologic  process.  Another  point  to 
note  just  here  is  that  these  toxins  are  apparently  harmful 

1  Abbott,  loc.  cit. 


IMMUNITY.  57 

to  the  bacteria  themselves  whenever  they  exceed  a  cer- 
tain amount,  as  is  shown  by  the  fact  that  most  of  the 
infectious  diseases  are  self-limiting,  and  by  the  cessation  of 
growth  and  even  the  death  of  the  germs  in  the  various 
culture-media  after  a  certain  length  of  time.  It  is  but  fair 
to  state,  however,  that  there  are  other  possible  explanations 
of  this  latter  phenomenon,  viz.,  an  increase  in  the  resist- 
ance of  the  infected  body  to  the  action  of  the  germs  and 
toxins,  or,  as  in  the  case  of  culture-media,  the  marked 
change  in  reaction  caused  by  the  bacterial  products. 

Immunity. — Having  thus  obtained  some  knowledge  of 
the  exciting  causes  of  infectious  diseases  and  of  how  they 
act,  one  of  the  most  important  considerations  is  in  relation 
to  the  prevention  of  the  incurrence  of  these  diseases  by  the 
well,  and  to  the  antagonizing  or  checking  of  the  further 
action  of  the  cause  in  those  already  infected.  It  is  well  to 
disinfect  and  to  destroy  disease  germs  whenever  and  wher- 
ever it  is  possible  to  do  so,  and  at  the  same  time  to  prevent 
in  any  manner  their  transferrence  from  unknown  or  inac- 
cessible sources  to  susceptible  persons,  but  it  is  still  better 
so  to  strengthen  and  fortify  the  human  body  that  the  mi- 
crobes, even  though  received  into  it,  will  be  unable  to  do 
it  harm.^  Naturally  our  first  desire  would  be  to  secure  a 
permanent  insusceptibility,  if  this  might  be  had  without  too 
^reat  risk  or  discomfort ;  but  since  this  is  rarely  possible 
M'ith  our  present  knowledge,  we  must  endeavor,  especially 
when  the  danger  of  infection  is  imminent,  to  secure  the 
greatest  possible  immunity  even  though  that  may  be  only 
temporary  or  incomplete.  Occasionally  we  find  indi- 
viduals that  possess  extreme  natural  immunity  to  certain 
maladies ;  observation  shows  that  most  well  persons  have 
fair  protection  in  the  case  of  ordinary  exposure  to  infec- 
tious matter;  and  further  investigation  teaches  that  this 


58  BA  CTERIOL  0  G  Y. 

protection  is  materially  affected  by  such  factors  as  one's 
state  of  health,  occupation,  age,  or  diet,  or  by  inmries, 
drugs,  fatigue,  exposure  to  heat  or  cold,  etc.  -^^ut  our 
desire  is  to  know  how  to  provide  a  positive  immunity 
against  each  infection  and  for  all  persons.  That  we  have 
the  means  of  producing  such  protection  in  the  case  of  one 
disease,  at  least,  is  well  shown  by  the  history  of  vaccina- 
tion ;  and  the  work  of  many  investigators  in  recent  years 
indicates  that  the  promise  of  similar  results  in  regard  to 
many  other  maladies  is  by  no  means  vain.  Certain  it  is 
that  many  human  beings  and  animals  have  been  rendered 
apparently  imnmne  to  other  fatal  diseases,  and  the  indica- 
tions point  to  the  probability  that  tlie  human  race  will 
shortly  have  the  same  protection  against  most  of  the  trans- 
missible maladies  that  it  now  has  against  smallpox. 

Just  here  it  may  be  well  to  consider  several  theories  that 
have  been  advanced  in  the  attempt  to  explain  the  phenom- 
ena of  immunity.  Of  these,  two  have  been  practically  dis- 
proved, viz.,  the  exhaudioii  theory  of  Pasteur,  which  was 
that  the  pathogenic  germs  in  their  process  of  growth 
in  the  body  removed  some  material  from  the  latter  neces- 
sary to  their  existence ;  and  the  diametrically  opposite 
retention  theory  of  Chauveau,  -which  was  that  the  germs 
produced  .some  substance  which  gave  immunity  as  long  as 
it  was  retained  in  the  tissues.  On  the  other  hand,  there 
are  strong  adherents  to  both  the  phagocytosis  theory  of 
]\Ietchnikoff  and  the  livmoraJ  theory  of  Biichner. 

The  phagocytosis  theory  is,  "that  immunity  against 
infection  is  essentially  a  matter  l)otween  the  invading 
bacteria  on  the  one  hand  and  tlic  Icucoeytes  of  the  ti.ssues 
on  the  other;  that  during  the  tirst  attack  of  the  disease  the 
white  lilood-corpuscles  gain  a  tolerance  to  the  poisons  of 
the  bacteria,  and  so  are  able  to  resist  the  next  incursions 


ANTITOXIN  THEORY.  59 

of  the  enemy  and  actually  to  attack  and  destroy  the  latter." 
Biiehner  has  apparently  shown  that  the  blood-plasma, 
especially  that  of  immune  animals,  is  bactericidal  to  many 
virulent  germs,  and  he  attributes  this  effect  to  the  pres- 
ence in  the  fluid  of  certain  proteid  substances  akin  to 
globulin.  These  he  terms  alexins,  from  a  Greek  word 
meaning  to  protect.  Further,  he  believes  that  they  act 
chemically  in  causing  death  of  the  disease  germs,  and 
that  the  increased  amount  of  alexins  in  the  blood  of  those 
who  have  acquired  immunity  is  brought  about  by  a  stimu- 
lation or  "reactive  change"  in  certain  cells  due  to  the 
presence  of  the  bacteria  or  their  products.  Moreover,  this 
humoral  theory  serves  to  account  for  the  natural  immu- 
nity possessed  by  some  individuals  and  animals,  their  body- 
juices  presumably  containing,  through  some  cause  or  other, 
an  extra  quantity  of  the  protective  proteids. 

But  an  essential  factor  in  securing  immunity  is  the 
power  of  the  body  to  resist  or  endure  the  poisons  produced 
by  the  disease  germs,  something  fully  as  important  as  its 
ability  to  destroy  the  infecting  organisms.  Consequently 
there  is  another  theory — that  of  the  antitoxins — which, 
in  view  of  recent  developments  and  the  fact  that  it 
is  capable  of  immediate  practical  application,  is  one  of 
the  most  important  thus  far  proposed.  It  is  M^ell  known 
that  the  human  system  has  the  power  of  tolerating 
or  accommodating  itself  to  the  action  of  almost  any 
toxic  substance — provided  the  latter  be  administered  at 
first  in  sufficiently  minute  doses  and  then  gradually 
increased — until  it  can  in  time  withstand  quantities  that 
would  quickly  prove  fatal  to  one  unaccustomed  to  the 
poison.  Elirlich  has  further  shown  that  with  the  toxic 
alkaloids  of  certain  higher  plants,  after  a  certain  degree 
of  tolerance  is  attained  the  administration  of  the  drug  may 


60  BA  CTERIOL  0  G  Y. 

be  much  more  rapidly  increased,  and  that  while  up  to  this 
point  no  apparent  change  occurs  in  the  body-fluids,  now, 
when  the  tolerance  becomes  so  much  increased,  a  new 
substance  is  produced  in  the  blood  which  is  capable  of 
neutralizing  the  poison  in  not  only  the  person  or  animal 
under  experimentation,  but  also  in  others  into  whom  it 
may  be  introduced.  Further  investigations  have  shown 
that  this  same  production  of  antidotal  or  antagonizing 
substances  may  be  brought  about  by  the  slow  adminis- 
tration of  the  toxins  of  pathogenic  bacteria — something 
not  hard  to  understand  when  we  remember  that  the 
bacterial  toxins  are  just  as  much  the  products  of  plant-life 
as  are  the  alkaloids  that  Ehrlich  used,  and  very  much 
like  the  latter  in  composition.  "Antitoxin  is  thus  chiefly 
known  to  us  as  a  specific  disease-resisting  constituent  of 
the  serum  of  immunized  animals." 

On  the  other  hand,  the  antitoxins,  as  these  substances 
antidotal  to  the  toxins  are  called,  have  been  found  to  be 
all)uminoid  in  character  and  similar  in  composition  to  the 
nucleins.  In  fact,  attempts  have  been  made  to  employ 
the  latter  in  place  of  or  in  conjunction  with  the  anti- 
toxins, with  results  that  have  not  been  altogether  without 
success. 

Much  credit  must  be  given  to  the  labors  of  Behring, 
Tloux,  Kitasato,  HafFkine,  and  others  for  the  development 
of  practical  methods  of  using  the  antitoxins,  methods 
which  are  now  recognized  as  eminently  proper  and  even 
superior  to  any  others  in  the  treatment  of  some  of  the 
most  virulent  diseases.  The  great  reduction  in  the  mor- 
tality from  one  disease  alone — diphtheria — already  attained 
through  the  application  of  this  treatment  almost  exceeds 
exj)ectation  and  belief,  and  the  promise  seems  now  to  be 
that  the  results  with  respect  to  cholera  and  other  deadly 


AXTITOXIN   THEORY.  61 

maladies  will  be  equally  brilliant  and  add  further  glorv  to 
this  new  science  of  bacteriology.  Comparatively  recently 
AVright  has  shown  that  the  blood  contains  certain  sub- 
stances M-hich  can  so  affect  disease-producing  bacteria  that 
the  leucocytes  may  destroy  them  by  phagocytosis.  These 
substances  which  he  calls  opsonins,  vary  not  only  in  quan- 
tity in  different  persons,  but  apparently  also  in  quality, 
there  being  probably  a  specific  opsonin  for  each  kind  of 
pathogenic  organism.  Moreover,  it  has  been  found  that 
in  many  cases  the  amount  or  influence  of  a  given  opsonin 
can  be  increased  in  the  blood  by  appropriate  inoculation 
of  sterilized  bacteria  of  its  particular  kind,  and,  secondly, 
that  bv  determining  a  patient's  opsonic  index  for  a  par- 
ticular disease  we  can  approximately  estimate  his  power 
of  resistance  or  degree  of  immunity  to  that  disease.  The 
opsonic  index  of  an  individual  is  the  ratio  between  the 
phagocytic  power  of  a  certain  number  of  leucocytes — as 
indicated  by  the  number  of  bacteria  taken  up  in  a  given 
time  when  acted  upon  by  a  unit  of  his  serum, — and  the 
power  of  the  same  number  of  the  same  kind  of  leucocytes 
when  acted  upon  by  a  unit  of  serum  from  a  normal  and 
healthy  person. 

To  some  it  may  seem  that  either  the  humoral  or  the 
antitoxin  theory  is  identical  with  the  discarded  retention 
theory  of  Chauveau  ;  but  it  should  be  noted  that  accord- 
ing to  the  latter  the  invading  microbes  themselves  produce 
the  antidote  or  antagonizing  substance,  while  Biichner's 
theory  attributes  this  production  to  the  integral  cells  of  the 
body,  which  furnish  the  alexins  normally  in  minute  quan- 
tities to  the  blo(jd,  and  asserts  that  the  latter  are  germicidal 
to  the  bacteria  themselves ;  and,  on  the  other  hand,  the 
antitoxins,  though  produced  like  the  alexins  by  body-cells. 


62  BACTERIOLOGY. 

probably  act  chemically  in  neutralizing  the  bacterial  poi- 
sons, and  are  dependent  upon  the  prior  presence  in  the 
body  of  the  toxins,  being  a  result  of  its  acquired  tolerance 
to  the  latter.  With  alexins  or  antitoxins  it  is  evident 
that  the  immunity  will  last  only  so  long  as  these  sub- 
stances remain  unchanged  in  the  blood. 

However,  there  is  no  reason  why  the  phagocytosis,  hu- 
moral, antitoxin,  and  opsonin  theories  should  not  mutually 
support  rather  than  tend  to  discredit  one  another.  There 
seems  to  be  good  evidence  of  the  phenomena  upon  which 
each  of  them  is  based,  and  even  with  our  present  incom- 
plete knowledge  of  the  blood  and  its  component  parts,  it 
is  not  difficult  to  conceive  that  while  the  alexins,  and  later 
the  antitoxins  and  opsonins  protect  the  leucocytes  by  weak- 
ening the  vitality  of  the  microbes  and  neutralizing  their 
products,  the  leucocytes  thus  guarded  and  in  full  vigor 
attack  and  make  way  with  the  bacteria,  which  have  lost 
their  power  for  evil.  In  other  words,  if  the  production 
of  the  toxins  of  an  infectious  malady  is  not  too  rapid, 
all  four  of  these  agents  may  combine  to  overcome  the 
enemy,  and  not  only  to  limit  the  disease,  but  also  to  give 
subsequent  immunity  for  a  more  or  less  prolonged  period. 

Much  consideration  has  lately  been  given  to  the  so- 
called  lateral  chain  theory  of  immunity  suggested  by 
Ehrlich  in  1897,  since  it  serves  better  than  anything  else 
to  aid  in  the  solution  of  many  of  the  problems  of  this 
abstruse  subject.  It  is  primarily  dependent  upon  the 
well-known  fact  that  many  poisons,  including  the  bacterial 
and  similar  toxins,  have  a  s])ecific  attraction  toward  and 
action  uj)on  certain  cells  of  the  body.  Ehrlich  assumes 
an  extremely  com])licated  cell  protoplasm  with  many 
affinities  for  combination  with  external  substances.  These 
affinities  may  be  hypothetically   and  graphically   repre- 


EHELICH'S  LATERAL   CHAIN  THEORY.  63 

sented  as  slight  protoplasmic  protrusions  on  the  contour 
of  the  cell-wall,  and  these  affinities  thus  materialized  he 
terras  "lateral  chains"  or  receptors.  Now  according 
to  their  particular  and  respective  affinities  the  receptors 
attract  to  themselves  the  various  molecular  food  particles 
tliat  the  cell  needs,  it  being  possible,  however,  for  one 
receptor  to  have  an  affinity  for  several  kinds  of  molecules. 
Such  molecules  capable  of  attraction  and  attachment  to 
the  receptors  are  termed  "  haptophores."  Accordingly, 
haptophores  of  a  poisonous  nature  that  have  either  entered 
or  been  created  in  the  body  may  become  attached  to  cer- 
tain receptors  of  a  given  cell,  and  if  of  sufficient  number 
and  virulence  may  altogether  check  the  nutrition  of  and 
destroy  the  cell ;  but  if  not  sufficient  in  number  and 
toxicity,  the  harmful  haptophores  only  stimulate  the  cell 
protoplasm  to  the  formation  of  many  new  receptors  of 
that  particular  kind  in  order  that  its  nutrition  may  be  main- 
tained ;  and  it  is  conceivable  that  through  continued  or  re- 
peated irritation  the  cell  may  create  many  more  receptors 
than  it  needs,  which  may  subsequently  be  separated  from  it 
and  thrown  off  as  particulate  bits  of  protoplasm,  each  with 
its  own  specific  affinities,  into  the  surrounding  fluids  and 
spaces  of  the  body.  Eventually,  then,  there  may  be  pre- 
pared enough  specific  and  extra  receptors,  either  attached 
to  or  dissociated  from  the  cells,  to  attract  and  unite  with 
all  the  toxic  haptophores  present,  so  that  the  cells  are  no 
longer  unduly  irritated,  but  perform  their  functions  in  a 
normal  manner.  So  also,  cells  primarily  lacking  the  ap- 
propriate receptors  are  immune  against  the  molecules  of 
a  given  poison. 

Ehrlich's  theory  goes  further,  and,  taking  into  consid- 
eration the  known  production  by  the  animal  body  under 
stimulation  of  particular  foreign   and  harmful  cells,  such 


64  BA  CTERIOL  0  G  Y. 

as  bacteria,  of  specific  substances  capable  of  dissolving  and 
destroying  the  invading  cells,  assumes  the  production  of 
aynbooeptors  that  will  bring  into  contact  and  union  the  sol- 
vent or  lysin  and  the  particular  cells  which  it  is  to  destroy. 

Thus  we  can  appreciate  the  identity  of  the  receptors 
and  antitoxins,  and  that  the  lysins  just  mentioned  corre- 
spond to  the  alexins  of  Biichner. 

"  Acquired  immunity  depends  upon  the  regeneration  of 
receptors  to  compensate  for  those  thrown  out  of  service  by 
union  with  useless  haptophores.  The  increasing  immunity 
characterizing  immunization  depends  upon  the  regenera- 
tion of  an  unlimited  number  of  receptors,  so  that  the  cell 
can  provide  for  the  ever-increasing  number  of  haptophores 
brought  to  it  and  still  have  enough  receptors  remaining 
to  carry  on  its  own  nutrition."  ^ 

Method  of  Preparing  Diphtheria  Antitoxin. — 
Within  a  comparatively  short  space  of  time  the  antitoxins 
have  been  discovered,  tried,  and  practically  adopted  by 
the  medical  profession  of  the  civilized  world  as  a  safe  and 
efficient  means  for  the  prevention  or  the  alleviation  and 
cure  of  several  of  our  most  dreaded  diseases.  A  short 
account  of  the  usual  method  of  preparing  the  antitoxin 
of  diphtheria  will,  therefore,  probably  not  be  uninter- 
esting. 

In  the  first  place,  it  is  necessary  that  the  toxin  of  the 
disease  should  be  produced,  which  is  commonly  done 
by  growing  the  specific  organism  in  peptone-bouillon. 
Wlien  this  has  attained  a  powerful  and  definite  virulence, 
as  detcrminetl  by  its  (ifiect  on  small  animals  of  known 
weight,  the  organisms  are  destroyed  by  some  germicide, 
such  as  trikresol,  or  more  coninionly  are  reniovetl  by 
careful  filtration  from  the  bouillon  whicii  holds  the 
'Medicine,  June,  I'JUo,  j).  -150. 


DIPHTHERIA  ANTITOXIN. 


65 


toxin  in  solution.  A  small  qaantity,  say  0.1  c.c.  of  the 
filtered  bouillon  is  then  injected  into  a  large  animal, 
such  as  the  horse,  Avhich  should  be  in  good  health, 
and   preferably  should  have   been  tested   previously  by 

Fig.  10. 


Filter  for  removing  baetetia  from  fluid  culture-media. 

inoculations  of  tuberculin  and  mallein  to  eliminate  the 
possibility  of  the  presence  of  tuberculosis  or  glanders. 
The  animal  manifests  for  a  few  days  the  disturbances 
peculiar  to  the  disease  in  question  but  usually  in  a  minor 
degree,  since  the  dose  was  purposely  quite  small  in  pro- 

FlG.  11. 


Roux  aseptic  hypodermic  syringe  for  administering  antitoxin. 


portion   to   its  weight;    as   soon  as   recovery  is   evident 
another  inoculation  of  an  increased  dose  is  made,  and  so 
on  until  experiment  shows  that  the  animal  can  withstand 
5 


6Q  £A  CTERIOLOG  Y. 

practically  an  unlimited  quantity  of  the  toxic  bouillon,  and 
certainly  an  amount  which  would  have  been  quickly  fatal 
before  the  first  inoculation.  This  is  evidence  that  the  anti- 
toxin has  been  produced  and  that  it  exists  in  approxi- 
mately sufficient  degree  in  the  blood-serum,  but  positive 
confirmation  is  secured  by  introducing  a  little  of  the 
horse's  blood  into  a  guinea-pig  or  other  small  animal  that 
has  received  a  fatal  dose  of  the  toxin  bouillon.  If  it  sur- 
vives, a  quantity  of  blood  is  then  drawn  with  the  strictest 
antiseptic  precautions  into  sterile  flasks  from  the  jugular 
or  other  large  vein  of  the  horse,  the  latter  returned  to 
its  quarters,  and  the  blood  set  aside  in  a  cool  place  to 
coagulate.  This  done,  the  clear  serum  containing  the  anti- 
toxin is  drawn  off  and  to  it  is  added  a  small  quantity  of 
trikresol  or  other  harmless  preservative. 

It  is  now  necessary  to  determine  the  strength  of  the 
serum.  The  fatal  dose  of  toxin  for  guinea-pigs  is  readily 
found  by  experiment.  Behring  therefore  suggested  in 
the  case  of  diphtheria  antitoxin  that  the  immunizing  unit 
be  taken  to  be  1  c.c.  of  a  serum  of  which  0.1  c.c.  would 
prevent  oedema  and  death  in  guinea-pigs  when  injected 
simultaneously  with  10  times  the  fatal  dose  of  the  toxin. 
In  other  words,  the  immunizing  unit  was  to  be  sufficient 
to  overcome  100  times  the  amount  of  the  toxin  required 
to  kill  a  guinea-pig. 

The  antitoxin  serums  now  administered  are,  however, 
much  stronger  than  this  normal  serum  of  Behring's,  10 
c.c,  the  amount  usually  injected,  being  equivalent  to 
from  600  to  2500  or  even  more  inmuuiizing  units,  the 
weaker  strength  being  used  for  inmiunizing  those  who 
have  not  as  yet  incurred  the  disease.  Much  depends 
upon  the  early  use  of  the  specific  antitoxin  in  cases  of 
diphtheria,  and  probably  also  in  the  other  diseases  for 


VALUE  OF  ANTITOXIN  TREATMENT.  67 

which  this  method  of  treatmeut  will  be  found  valuable. 
It  is  not  to  be  supposed  that  the  remedy  has  any  power 
to  repair  the  organic  lesions  which  have  been  caused 
by  the  action  of  the  powerful  toxins.  That  the  antitoxin 
treatment  is  invaluable  cannot  be  doubted.  The  statistics 
of  Prof.  Welch,  of  Johns  Hopkins  Hospital,  founded 
on  a  very  large  number  of  diphtheria  cases,  "show  an 
apparent  reduction  of  case-mortality  of  55.8  per  cent.," 
and  where  the  application  was  made  in  the  first  three 
days  of  the  disease  the  mortality  was  only  8.5  per  cent, 
in  over  1100  cases  as  against  a  mortality  of  30  per  cent, 
or  higher  under  former  methods  of  treatment.  Another 
interesting  report  is  that  of  the  Chicago  Department  of 
Health  for  1896.  In  that  city  in  that  year  there  were 
2436  cases  of  true  diphtheria  verified  bacteriologically. 
The  antitoxin  was  administered  to  2302  of  these,  with  a 
resultant  mortality  of  only  6.56  per  cent.,  or  151  deaths. 
Moreover,  2016  other  persons  exposed  to  the  disease  were 
inoculated  with  the  antitoxin  in  order  to  immunize  them, 
and  of  these,  only  14  subsequently  contracted  the  malady, 
and  none  died.  Moreover,  the  average  yearly  death-rate 
from  diphtheria  and  croup  in  Chicago  for  the  pre-anti- 
toxin  decade  (1886-1895)  was  14.02  per  100,000  of  popu- 
lation, as  against  4.18  in  the  antitoxin  decade  (1896-1905) 
and  2.17  for  1905.  In  other  words,  notwithstanding  a 
great  increase  in  population,  the  average  yearly  deaths 
from  these  diseases  dropped  from  1423  for  the  first  decade 
to  693  for  the  second,  and  to  433  for  1905.  Further 
comment  seems  unnecessary,  but  the  statistics  of  the 
United  States  Census  already  quoted,  showing  a  reduction 
of  over  two-thirds  in  the  death-rate  from  this  disease 
from  1890  to  1905  (from  70.1  to  19.9  per  100,000)  in 
almost  one-half  the  population  of  the  whole  country,  is 


68  BACTERIOLOGY. 

even  more  striking,  especially  as  the  gain  must  be  attrib- 
uted almost  entirely  to  the  adoption  and  use  of  the  anti- 
toxin. The  results  have  been  so  positive,  the  advance  so 
progressive,  and  any  changes  in  the  previous  methods  of 
treatment  of  the  disease  so  slight  as  to  preclude  the  possi- 
bility of  doubt  as  to  the  wisdom  of  employing  it  both  as 
a  remedy  and  as  a  prophylactic. 

The  immunity  secured  by  the  use  of  an  antitoxin  is 
almost  immediate,  an  advantage  often  of  the  greatest 
importance  ;  but  since  it  is  passive,  the  antitoxin  having 
been  developed  outside  of  the  person  protected,  it  is  more 
or  less  transient,  and  the  inoculation  must  be  repeated  at 
intervals,  or  when  danger  of  new  infection  is  imminent. 
The  same  remarks  apply  to  the  use  of  anthnicrobin,  the 
product  resulting  from  the  gradual  introduction  of  the 
bodies  of  the  bacteria  rather  than  their  toxins  into 
susceptible  and  suitable  animals.  This  gives  rather  a 
bacteriolytic  form  of  immunity,  and  thus  far  is  not  so 
satisfactory  as  that  due  to  antitoxin. 

On  the  other  hand,  immunity  that  is  acquired  actively, 
either  by  accident  or  by  deliberate  experiment,  is  slower 
in  developing,  but  much  more  likely  to  be  permanent.  It 
is  a  result,  as  we  know,  of  most  of  the  spontaneous  infec- 
tious diseases,  though  its  duration  in  some  cases  is  briefer 
than  we  desire.  It  may  also  be  secured  by  prophylaetic 
infection  or  by  prophylactic  intoxication.  In  the  former 
we  may  use  virulent  infective  matter  in  much  reduced 
doses  or  quantities,  or  better  and  more  safely  as  far  as 
man  is  concerned,  some  form  of  attenuated  virus  may  be 
employed,  the  infecting  matter  liaving  been  modified  by 
development  in  animals  of  another  species,  by  heat,  light, 
drying,  electricity,  growtli  in  nnfavorable  media,  etc. 
As   an    illustration,  we  have  tlie  modern  vaccine  virus 


PROPHYLACTIC  INFECTION.  69 

derived  from  the  cow  which  has  entirely  supplanted  the 
former  direct  inoculation  of  matter  from  the  human  small- 
pox patient.  As  for  prophylactic  intoxication,  we  may 
use  either  the  dead  bodies  of  the  infectious  bacteria,  as 
has  been  done  by  Haff  kine  in  his  work  against  plague  and 
cholera,  or  the  products  of  the  organisms  derived  from 
artificial  cultures,  as  indicated  in  describing  the  produc- 
tion of  antitoxin.  Various  factors,  some  still  unsettled, 
must  determine  the  advisability  of  the  use  in  a  given  case 
of  one  or  another  of  the  above  methods ;  but  it  must  be 
remembered  in  regard  to  actively  acquired  immunity,  that 
not  only  is  it  at  times  too  slow  in  development  to  be  of 
value  after  infection  has  occurred,  but  also  that  "  the  in- 
troduction of  toxins  or  bacterial  proteids  after  the  onset 
of  the  disease  may  be  not  merely  useless,  but  actually 
harmful  by  adding  to  the  sum  total  of  toxic  material 
against  which  the  tissues  struggle." 

^Nevertheless,  experience  will  continue  to  show  that 
whether  one  or  all  of  these  methods  of  securing  immunity 
may  be  employed  or  whether  others  by  which  the  body 
can  protect  itself  may  be  discovered,  sanitation  and  a  con- 
dition of  perfect  health  throughout  the  system  are  of  the 
utmost  importance  in  warding  off  attacks  of  or  in  securing 
immunity  from  any  of  the  pathogenic  organisms,  and  in 
withstanding  their  ravages  should  disease  be  incurred. 
A  sound  body  therefore  is  a  most  vitally  active  and  not 
simply  a  passive  agent  for  the  prevention  of  such  diseases. 


CHAPTER    III. 

THE  ATMOSPHERE— AIE. 

The  composition  of  the  atmosphere  surrounding  the 
earth  is  remarkably  uniform.  It  is  practically  always 
the  same  everywhere  provided  no  obstacle  be  interposed 
to  the  action  of  those  natural  forces  by  which  this  uni- 
formity is  maintained.  This  atmosphere  is  estimated  to 
be  about  forty  miles  in  depth,  and  its  weight-pressure, 
of  which  we  have  a  visible  manifestation  in  the  action  of 
the  barometer,  upon  the  total  surface  of  the  adult  human 
body  is  equivalent  to  that  of  about  fourteen  tons.  Any 
considerable  variation  in  this  pressure  may  give  rise  to 
disturbances  of  health  more  or  less  serious,  such  as  the 
cardiac  derangements  and  "  mountain  sickness "  experi- 
enced by  strangers  visiting  high  altitudes,  or  the  "  caisson 
disease  "  of  those  who  work  in  a  compressed  atmosphere. 
In  fact,  it  is  not  improbable  that  some  of  the  vague  dis- 
turbances of  comfort  to  which  a  large  class  of  persons  are 
subject  during  changes  of  the  weather  will  hereafter  be 
found  to  be  due  to  the  variations  in  this  pressure  wliich 
are  constantly  occurring  everywliere. 

The  average  composition  of  the  air  in  its  normal  state 
is  about  as  follows  :  oxygen,  20.96  per  cent,  by  volume ; 
nitrogen  and  argon,  79  ])er  cent. ;  carbon  dioxide,  0.04 
per  cent. ;  aqueous  vapor,  varying  in  amount  with  the  tem- 
perature and  other  conditions;  a  trace  of  ammonia,  and  a 
variable  amount  of  ozone,  organic  matter,  sodium  salts,  etc. 
70 


COMPOSITION  OF  AIR. 


71 


The  variation  in  the  percentage  of  oxygen  may  be  from 
20.87  in  towns  to  20.98  in  pure  mountain  air  or  far  out  at 
sea;  in  the  percentage  of  carbon  dioxide,  from  0.02  to 
0.05.     So  far  as  we  know  at  present,  the  nitrogen  variation 


Fig.  12. 


M.M.Hg. 

ALTITUDE 

/  AFTER    \ 

6000  FT.              14130  FT.        14130  FT.  (sM  hrs.) 

PULSE 
RATE 

100 

135 

/ 

95 

/ 

/ 

90 

130 

,y 

85 

o-'-' 

,**»^ 

80 

125 

<v 

75 

\ 

V 

120 

V 

^^ 

"•^^ 

115 

PULSE  RATE- 


BLOOD  PRESSURE- 


Average  blood  pressure  and  pnlse  rate  of  twenty-two  young  men.  Adapted 
from  papers  of  Drs.  Gardner  and  Hoagland  in  the  Transactions  of  the  American 
riimatological  Association,  vol.  xxi.,  1905,  p.  85. 


is  ahnost  infinitesimal.  The  air  is  a  mechanical,  not  a 
chemical  mixture,  and  there  is  always  some  change  taking 
place  in  the  proportions  of  tlie  various  constituents. 
However,  the  mixture  is  maintained  in  its  wonderful  uni- 


72  THE  ATMOSPHERE— AIR. 

formity  by  the  interdependent  action  of  plants  and  ani- 
mals, and  by  the  diffusion  of  gases,  the  law  of  which  is 
that  '^  a  gas  expands  into  a  space  in  which  there  is  another 
gas  as  freely  and  as  rapidly  as  if  there  were  a  vacuum." 
Though  this  agency,  like  the  other,  is  continually  operat- 
ing, its  results  are  greatly  facilitated  by  adventitious  air- 
currents  and  by  the  application  of  heat.  When  a  gas  is 
thus  diffused,  it  will  not  separate  again  from  the  others 
under  ordinary  circumstances. 

Oxygen  is  the  most  important  of  the  above  constituents. 
It  supports  all  animal  life  ;  oxidizes,  destroys,  and  renders 
harmless  organic  impurities,  and  by  oxygenating  the  blood 
and  oxidizing  the  food  for  our  tissues  gives  heat  and 
energy,  the  vital  source  of  all  our  thoughts  and  actions. 
The  supply  to  the  atmosphere  is  constantly  maintained  by 
the  higher  plant-life,  which  decomposes  carbon  dioxide 
and  gives  off  oxygen  to  the  air.  In  man  the  greatest 
limit  of  life  without  oxygen  or  air  is  about  four  minutes. 
A  decrease  in  the  proportion  of  oxygen  in  the  air  does 
not  manifest  itself  by  untoward  symptoms  in  the  human 
])ody  until  there  is  less  than  13  percent,  by  volume ;  then 
as  it  falls  lower  and  lower  the  respirations  become  slower, 
deeper,  and  more  difficult,  less  oxygen  is  al)sorbed  by  tlie 
bh)(»(l,  and  there  follow  dyspnoea,  aspliyxia,  and  death. 
Tliis  may  occur  within  a  short  time  when  the  percentage 
goes  l)elow  8  per  cent.,  and  fatal  asphyxia  supervenes  very 
rapidly  when  there  is  as  little  as  3  per  cent,  of  oxygen. 

The  main  function  of  the  nitrogen  of  the  atmosphere 
.seems  to  be  to  act  as  a  diluent  and  to  prevent  the  too 
energetic  action  of  the  oxygen.  We  know  now,  however, 
that  at  least  one  family  of  ]>lants — the  leguminosie — is 
able,  V)y  the  aid  of  certain  bacteria,  to  take  nitrogen  almost 
directly  from  the  air  and  to  .store  it  for  animal  use  in  the 


CARBOX  DIOXIDE  IN  AIR.  73 

form  of  proteids.  The  ammonia  ever  present  in  the  air 
is  also  a  source  of  nitrogen  food  for  some  plants. 

The  gaseous  element  argon,  discovered  in  1894  by 
Lord  Rayleigh  and  Prof.  Ramsay,  comprises  about  1  per 
cent,  of  what  has  heretofore  been  considered  atmospheric 
nitrogen.  Thus  far  little  is  known  concerning  it  except 
that  its  atomic  weight  is  probably  somewhat  less  than  40, 
its  density  about  20,  and  that  it  is  very  inert,  though 
Berthelot  has  succeeded  in  making  it  combine  with  nas- 
cent vapors  of  benzene  under  the  influence  of  an  elec- 
ti'ical  discharge.  That  it  is  a  constant  component  of  the 
atmosphere  for  some  definite  purpose  is  more  than  prob- 
able, but  what  this  purpose  may  be  is  as  yet  unknown. 

The  carbon  dioxide^  present  in  the  atmosphere  is  of  no 
direct  use  to  animals,  but  is  essential  to  the  support  of 
vegetable  life,  furnishing  part  of  the  carbon  necessary  for 
the  formation  of  the  carbohydrates  and  proteids,  which  are, 
next  to  water,  the  main  constituents  of  plants.  The  pro- 
portion of  carbon  dioxide  in  the  out-door  air  varies  some- 
what from  time  to  time,  owing  to  the  changing  conditions. 
It  is  washed  out  of  the  air  by  rain,  and  there  is  therefore  less 
after  a  heavy  storm  ;  plants  absorb  it  by  day,  and  some  give 
off  a  slight  quantity  by  night ;  the  strata  of  the  atmosphere 
near  the  ground  receive  an  excess  of  it  from  the  soil-air; 
it  is  a  constant  product  of  combustion  and  of  the  decom- 
position of  organic  matter  by  saprophytic  bacteria,  etc. 
Tliough  heavier  than  air,  it  is  comparatively  evenly 
distributed  through  the  atmosphere  by  the  force  of  diffu- 
sion. 

The  normal  proportion   in  the  atmosphere  varies  from 

0.02  per  cent,  to  0.05   per   cent.,  but  we   may  take  the 

average  to  be  about  0.04  per  cent.     Should,  however,  any 

1  Carbon  dioxide  =  carbonic  acid  gas  =  carbonic  anhydride  =  CO2. 
Carbon  monoxide  =  carbonous  oxide  =  CO. 


74  THE  ATMOSPHERE — AIR. 

important  tests  of  the  amount  in-doors  be  required,  the 
percentage  in  the  out-door  air  at  that  particular  time  and 
place  should  also  be  determined  for  the  sake  of  accuracy. 
Within  the  limits  just  given, the  carbon  dioxide  cannot  be 
considered  as  an  impurity  of  the  atmosphere,  for  it  is  ever 
present  in  the  air,  and  is  as  necessary  to  plant-life  as 
oxygen  is  to  animals.  It  is  derived  from  the  combus- 
tion of  carbonaceous  materials,  from  the  exhalations  and 
excretions  of  animals  and  men,  and,  as  was  indicated,  in 
large  measure  from  the  action  of  the  saprophytic  bacteria 
and  also  of  the  budding  fungi  upon  organic  matter. 
Moreover,  any  excess  above  the  normal  percentage  as 
given  is  to  be  regarded  not  so  much  as  an  impurity  as  an 
indication  that  certain  processes  are  at  work,  which  by 
their  other  products  may  make  tlie  air  impure  and  unsafe 
for  human  use. 

The  amount  of  aqueous  vapor  in  the  atmosphere  varies 
from  time  to  time  because  the  factors  governing  it — con- 
densation and  evaporation — are  continuously  in  action, 
these  depending,  of  course,  mainly  upon  the  continual 
variations  in  temperature.  There  is  probably  never  a 
})erfectly  dry  air  unless  it  is  made  so  artificially,  and 
precipitation  occurs  the  moment  complete  saturation  is 
reached.  The  range  of  relative  humidity  is  probably 
from  30  to  100  per  cent.,  this  being  equivalent,  according 
to  the  temperature,  to  a  water-content  of  from  1  to  12  or 
14  grains  to  tlie  cubic  foot  of  air.  The  most  satisfactory 
])r()[)orti()n  for  health  has  not  been  experimentally  deter- 
mined, but  is  generally  considijred  to  l)e  from  05  to  75 
per  (X'lit.  when  the  temperature  is  moderate.^ 

'  Wlieu  the  tcni|)(M'iiture  is  iii)\var(l  of  80°  F.  a  liiiinidity  of  but  little 
over  70  per  cent,  may  be  vei-y  uncomfortable  and  depressing  if  the  air  is 
still  and  evai)oration  from  the  body  surface  thus  impeded.  A  breeze 
makes  even  a  hifrher  humidity  less  noti(H;able. 


ATMOSPHERIC  IMPURITIES.  75 

In  the  out-door  air  there  is  at  least  a  trace  of  ammouia 
either  free  or  combined,  a  small  amount  of  the  salts  of 
sodium  (especially  near  the  sea)  and  of  other  metals, 
and  a  trace  of  organic  matter.  This  last  is  part  of  the 
animal  and  vegetable  debris  of  the  earth ;  when  above 
a  trace,  it  is  to  be  treated  as  an  impurity,  as  should  any 
excess  of  ammonia. 

Minute  particles  of  innumerable  substances  are  being 
constantly  thrown  off  into  the  atmosphere,  and  it  is 
only  the  unceasing  action  of  nature's  purifying  powers 
that  keeps  the  proportion  within  the  limits  of  safety  to 
the  human  race.  Solid  particles,  lifted  up  by  the  winds, 
fall  to  the  earth  again,  or,  if  organic,  are  partially  oxi- 
dized and  decomposed  by  the  oxygen  and  ozone.  The 
gases  are  diluted  and  diffused  so  as  to  be  no  longer  harm- 
ful, or  are  decomposed,  or  are  washed  back  to  the  earth 
by  rain  or  snoAV.  The  great  volume  of  carbon  dioxide  is 
kept  within  bounds  by  the  action  of  the  vegetable  world. 
The  natural  purifiers  of  the  atmosphere,  therefore,  are 
the  force  of  gravity,  diffusion,  dilution  by  the  air  itself, 
winds,  oxidation,  rain,  and  the  action  of  plant-life ; 
and  so  exactly  are  these  adjusted  to  their  work  that 
never,  Avhen  they  have  fair  opportunity  to  act,  does  the 
composition  of  the  air  vary  much  from  the  normal  _ for 
any  great  length  of  time. 

The  impurities  in  the  atmosphere  that  are  especially 
liable  to  have  a  deleterious  influence  upon  health  may  be 
classed  as  follows :  1.  Suspended  matters.  2.  Gaseous 
and  semi-gaseous  substances,  including  :  3.  Those  espe- 
cially due  to  respiratory,  combustion,  and  decomposition 
processes,  and  Avhich  are  particularly  liable  to  contaminate 
tlie  air  of  dwellings  or  inhabited  apartments. 

The  most  important  suspended  matters  are  sand,  dust. 


76  THE  ATMOSPHERE— AIR. 

soot,  pollen  of  various  plants,  micro-organisms  of  all 
kinds,  particles  of  epithelia  and  other  excreta  thrown 
off  from  animal  bodies,  and  finely  divided  substances 
characteristic  of  certain  trades  or  industries.  These  may 
do  harm  by  clogging  the  air-vesicles  of  the  lungs  and 
thus  obstructing  respiration,  though  it  is  doubtful  whether 
their  action  is  ever  only  so  mild  or  simple ;  by  their 
irritant  action  upon  the  respiratory  passages ;  ^  by  being 
in  themselves  poisonous  or  hostile  to  the  system,  or,  as  in 
the  case  of  micro-organisms,  by  the  influence  they  have 
in  the  causation  of  disease.  Disease  germs  may  lodge  in 
the  respiratory  passages  and  do  harm,  or  may  be  swal- 
lowed and  so  cause  maladies,  such  as  typhoid  fever  or 
cholera,  which  primarily  affect  the  digestive  tract. 
-^  It  is,  howevei',  questionable  whether  pathogenic  organ- 
isms, especially  the  bacteria,  are  commonly  to  be  found 
dissociated  from  other  substances  floating  in  the  air.  Ex- 
periments by  Cornet  and  others  seem  to  show  that  such 
microbes  are  more  apt  to  be  adherent  to  dust  particles, 
^particularly  those  of  organic  nature,  and  it  is  probable 
that  free  bacteria  in  the  out-door  atmosphere  could  not 
long  maintain  their  vitality  deprived  of  nutriment  and 
exposed  to  the  action  of  light  and  oxygen.  Besides, 
they  are  so  quickly  dispersed  and  reduced  in  numbers  in 
any  reasonable  volume  of  unconfined  air  that  the  occa- 
sions must  be  rare  indeed  when  they  could  thus  cause 
disease.  In-doors,  especially  where  ventilation  is  neg- 
lected, the  case  is  different,  and  there  is  no  doubt  that  the 
air  frequently  becomes  the  carrier  of  dangerous  pathogens. 

'  The  pollen  from  certain  varieties  or  species  of  plants  is  thought  by 
luiiny  to  have  a  specific  influence  in  the  causation  of  hay-fever  and 
similar  ills,  and  there  seems  to  be  no  doubt  that  it  is  frequently  an 
aggravating  and  predisposing  factor  in  the  development  or  course  of  such 
disturbances. 


.  IMPURITIES  IN  DWELLINGS.  11 

We  must  also  make  a  distinction  as  to  whether  the 
other  sohd  impurities  are  found  in  the  out-door  air  or  in 
enclosed  spaces ;  and  if  in  the  latter,  whether  in  healthful 
dwellings,  in  sick-rooms  and  hospitals,  or  in  workshops 
and  factories.  Out-of-doors,  dust,  sand,  soot,  pollen,  waste 
dirt  from  dwellings,  street  refuse,  and  the  remains  of 
plant  and  animal  life  will  predominate  ;  in-doors  the  par- 
ticles will  be  more  limited  in  variety,  but  not  in  impor- 
tance. Among  them  will  be  epithelial  and  other  cells, 
possibly  pus-corpuscles,  hair,  bits  of  clothing,  food,  etc. 
One  may  also  find  arsenical  or  other  poisonous  dust 
from  wall-paper  or  paint.  In  sick-rooms  and  hospitals 
there  will  probably  be  pus-cells,  mycelia,  bacteria,  etc. 
Mills,  factories,  and  mines  have  their  special  atmospheres 
laden  with  particles  peculiar  to  the  occupation,  which  in 
many  cases  have  a  marked  influence  for  harm  on  the 
health  of  the  workers.  ^ 

The  gaseous  and  semi-gaseous  impurities  of  most  im- 
portance are  those  resulting  from  human  respiration  and 
cutaneous  exhalations,  products  of  combustion,  peculiar 
gases  in  sewer-air  or  soil-air,  organic  emanations  and 
vapors  from  decomposing  animal  and  vegetable  matter, 
and  the  volatile  substances  that  characterize  the  various 
atmospheres  in  and  about  gas-works,  factories,  and  other 
places  of  industry.  Chemically,  they  may  be  classified 
as  the  compounds  of  carbon  and  of  sulphur  with  oxygen 
and  hydrogen,  ammonia  compounds,  volatilized  minerals 
and  mineral  acids,  and  many  gaseous  and  semi-gaseous 
matters  of  organic  nature  but  indeterminate  composition. 

Inasmuch  as  certain  of  these  impurities,  viz.,  human 
exhalations,  combustion-products,  and  not  infrequently 
the  so-called  sewer-gas,  are  particularly  liable  to  be  found 
together  as  contaminants  of  the  atmosphere  of  inhabited 


78  THE  ATMOSPHERE — AIR. 

rooms  and  dwelliiiii'-,  it  will  lie  advisable  to  consider  them 
in  a  class  by  themselves,  and  to  study  their  effect  upon 
liealth  both  collectively  and  singly. 

The  volatile  excreta  from  the  lungs  and  skin  are  carljon 
dioxide,  aqueous  vapor,  and  a  considerable  amount  of 
nitrogenous  organic  matter,  to  -which  the  term  "crowd- 
poison"  is  sometimes  given.  As  products  of  combustion 
from  the  ordinary  lighting  and  heating  apparatus  of 
dwellings  we  may  have  carbon  dioxide,  carbon  monoxide, 
sulphur  dioxide,  ammonia  (with  possibly  its  sulphide), 
and  aqueous  vapor.  Of  sewer-gas  and  soil-air  we  shall 
speak  later. 

Carbon  dioxide,  contrary  to  the  general  opinion,  cannot 
be  said  to  be  directly  harmful  to  health  in  the  propor- 
tions in  which  it  is  likely  to  be  found  in  any  dwelling 
or  inhabited  apartment.  Although  present  to  the  ex- 
tent of  not  more  than  0.05  per  cent,  in  normal  out-door 
air,  numerous  experiments  indicate  that  both  men  and 
animals  mav  inhale  much  larger  proportions  than  this 
without  apparent  harm  provided  the  percentage  of  oxygen 
in  the  air  be  maintained  at  or  above  the  normal  ;  an 
increase  of  the  carbon  dioxide  from  other  sr)urces  than 
respiration  and  combustion  seems  to  have  no  appreciable 
per  cent.,  and  some  men  work  daily  in  atmospheres  con- 
taining almost  this  amount  as  a  result  i)f  their  peculiar 
occupations.  Dyspnrea  does  not  ])egin  to  occur,  and  then 
only  in  some,  until  the  percentage  goes  above  .3  or  4. 
In  quantities  above  these  figures  there  is  much  difference 
of  opinion  as  to  the  effect  of  the  gas  upon  tlie  human 
economy,  and  the  writer  is  not  aware  that  it  has  ever 
been  determined  just  what  percentage  is  fatal,  Parkes 
states   the   lethal    jjroportion    to    be    from    o    to    10   per 


CARBON  DIOXIDE  IN  DWELLINGS.  79 

cent.;  while  another  authority  states  that  animals  may 
be  kept  for  a  long  time  in  an  atmosphere  in  which 
there  is  a  high  jjercentage  of  carbon  dioxide  provided 
the  percentage  of  oxygen  be  increased  at  the  same  time. 
Hi  me  says  that  "  it  may  be  assumed  that  10  or  20  per 
per  cent,  is  a  dangerous  amount";^  but  Wilson^  shows 
that  air  having  from  25  to  30  per  cent,  may  be  inhaled 
with  impunity.  It  is  to  be  understood  that  the  above 
percentages  are  all  by  volume. 

According  to  his  weight,  an  adult  man  at  rest  absorbs 
from  15  to  18  cubic  feet  of  oxygen  and  exhales  from 
12  to  14  cubic  feet  of  carbon  dioxide  in  twenty-four 
hours.  Reichert^  says  :  "  The  amount  of  O  varies  from 
600  to  1200  grammes  (15  to  30  cubic  feet)  per  diem, 
and  that  of  CO,  from  700  to  1400  grammes  (12.5  to  25 
cubic  feet)  —  approximate  averages  being  about  750 
grammes  of  O  and  875  grammes  of  CO2."  According  to 
Ott/  ''  The  amount  of  water  thrown  oif  daily  is  about  a 
pound  ;  of  oxygen  taken  in,  about  a  pound  and  one-half; 
and  of  carbonic  acid  thrown  off,  a  little  more  than  a 
pound  and  one-half."  The  minimum  excretion  per  hour 
may  therefore  fairly  be  taken  to  be  about  0.7  cubic  foot 
of  carbon  dioxide  for  adult  men  and  0,6  cubic  foot  for 
women  or  for  each  person  of  a  mixed  assemblage.  Now, 
granting  the  presence  of  a  single  adult  occupant,  it  is 
evident  that  it  would  require  many  hours  before  a  room 
of,  say,  1000  cubic  feet  capacity  would  lose  sufficient 
oxygen  or  gain  sufficient  carbon  dioxide  to  produce  the 
slightest  apparent  harmful  results,  even  though  ingress  of 
fresh  air  were  prevented  ;  and  yet  experience  tells  us  that 

1  Stevenson  and  Mnrphy,  vol.  i.,  p.  945. 
^  American  Journal  of  Pharmacy,  1893,  p.  561. 
'  American  Text-book  of  Physiology,  p.  536. 
*  Text-book  of  Physiology,  first  ed.,  p.  270. 


80  THE  ATMOSPHERE— AIR. 

the  atmosphere  of  such  a  room  will  become  exceedingly 
foul  and  actually  detrimental  to  health  long  before  the 
lapse  of  time  necessary  to  exhale  sufficient  carbon  dioxide 
to  induce  serious  effects.  Moreover,  carbon  dioxide  is 
odorless,  while  the  air  of  inhabited,  unventilated  rooms  is 
characterized  by  a  decidedly  offensive  smell  that  remains 
for  some  time  even  after  adequate  ventilation  has  been 
secured  and  when  chemical  tests  show  the  percentage 
of  carbon  dioxide  to  have  been  reduced  to  nearly  the 
- — 4iprmjd.  "  The  chemical  analyses  of  the  air  of  over- 
crowded rooms,  and  the  experiments  upon  animals  made 
by  many  investigators,  indicate  that  the  evil  effects  ob- 
served are  probably  not  due  to  the  comparatively  small 
proportions  of  carbonic  acid  usually  found  under  such  cir- 
cumstances. .  .  .  The  proportion  of  increase  of  CO2  and 
of  diminution  of  oxvgen  which  has  been  found  to  exist  in 
badly  ventilated  churches,  schools,  theatres,  etc.,  is  not 
sufficiently  great  to  account  satisfactorily  for  the  great  dis- 
comfort which  such  conditions  produce  in  many  persons, 
and  there  is  no  evidence  that  such  an  amount  of  change 
in  the  normal  proportion  of  these  gases  has  any  influence 
upon  the  increase  of  disease  and  death-rates  which  statisti- 
cal evidence  has  shown  to  exist  among  persons  living  in 
crowded  and  unventilated  rooms."  ^  Therefore,  it  must 
be  something  other  than  carbon  dioxide  that  danger- 
ously pollutes  the  air  of  dwellings  and  necessitates  the 
provision  of  some  system  of  ventilation.  However,  witli 
our  present  knowledge  we  cannot  say  that  a  diminution 
of  oxygen  and  an  increase  of  carbon  dioxide  in  the  atmos- 
phere whicli  one  breathes  habitually  do  not  tend  to  lower 

1  "The  Composition  of  Expired  Air  and  its  Effect  upon  Animal  Life." 
Mitchell,  Billings,  and  Bergey,  No.  9S9,  vol.  xxix.,  Smithsonian  C'outribu- 
tious  to  Knowledge. 


EFFECT  OF  EXCESSIVE  HUMIDITY.  81 

the  general  tone  and  perhaps  the  bactericidal  powers  of 
the  body  and  thus  to  render  it  more  susceptible  to  dele- 
terious influences,  and,  since  there  is  some  evidence  that 
as  the  carbon  dioxide  in  the  atmosphere  increases  there  is 
a  lessening  of  the  amount  of  this  gas  excreted  from  the 
body,  it  will  on  general  principles  always  be  wiser  to  use 
every  reasonable  means  to  maintain  the  normal  propor- 
tion of  the  various  gases  in  tlie  atmosphere.  Moreover7 
the  fact  that  tuberculous  patients  usually  improve  if  they 
live  continuously  out  of  doors  would  indicate  that  the  full 
quota  of  oxygen  in  the  air  is  essential  to  the  best  interests 
of  health,  and  also  that  indoor  air,  though  apparently  but 
slightly  impure,  favors  the  development  and  progress  of 
this  disease.  < 

Aqueous  vapor  is  another  of  the  substances  excreted 
continually  from  both  the  lungs  and  the  skin ;  but  it  is 
obvious  that  in  itself  it  cannot  be  directly  harmful  to  the 
system,  for  we  find  it  ever  present  in  all  natural  atmos- 
pheres, and  are  continually  replacing  by  imbibition  its  loss 
from  our  bodies.  The  quantity  daily  thrown  off  from 
the  lungs  and  skin  will  depend  on  the  temperature  and 
humidity  of  the  atmosphere,  the  quantity  of  air  inspired 
and  water  imbibed,  and  many  other  factors ;  but  under 
ordinary  conditions  the  average  excretion  will  be  from 
100  to  1700  grammes  (about  3.5  to  60  fluidounces),  though 
increased  exertion  might  cause  even  the  latter  amount  to 
be  greatly  exceeded.  It  is  accordingly  possible  that  this 
large  quantity  of  moisture,  tending  to  saturate  an  atmos- 
phere already  humid,  might  indirectly  and  reflexly  check 
the  excretion  of  waste  matters  by  the  sweat-glands  by 
preventing  evaporation  from  the  skin,  and  that  the  reten- 
tion of  these  wastes  in  the  system  may  help  to  produce 
the  depression,  headache,  and  other  symptoms  experi- 
6 


82  THE  ATMOSPHERE— AIR. 

enced  by  those  breathing  foul  air.  It  has  been  noticed 
that  these  symptoms  due  to  foul  air  are  more  readily 
manifested  when  the  temperature  of  the  atmosphere  is 
much  below  or  much  above  the  usual  room-temperature 
of  65°  to  70°  F.  At  low  temperatures  the  air  is  readily 
saturated,  and  beside,  the  excreting  action  of  the  skin 
is  much  lessened  by  the  cold ;  at  high  temperatures  the 
humidity  is  often  already  near  the  saturation-point,  while 
the  external  heat  tends  to  increase  the  quantity  of  water 
given  off  by  the  lungs  and  skin.  "  At  high  tempera- 
tures the  respiratory  centres  are  affected  where  evapora- 
tion from  the  skin  and  mucous  surfaces  is  checked  by 
the  air  being  saturated  with  moisture — at  low  tempera- 
tures the  consumption  of  oxygen  increases  and  the  demand 
for  it  becomes  more  urgent."  ^  At  70°  F.  the  aqueous  ex- 
halation from  an  adult  body  would  in  an  hour  or  less  com- 
pletely saturate  from  350  to  600  cubic  feet  of  air  having 
the  not  unusual  relative  Immidity  of  75  per  cent,,  while 
at  80°  F.  an  equal  or  even  greater  volume  of  air  would 
doubtless  gain  its  maximum  of  moisture  from  the  increase 
of  perspiration  due  to  the  extra  heat.  Moreover,  as  evapo- 
ration of  the  perspiration  is  one  of  the  most  important 
means  for  maintaining  the  balance  between  heat-production 
and  heat-dissipation,  interference  M'itli  this  process  natur- 
ally tends  to  raise  the  body-temperature  rapidly  and 
to  produce  the  consequent  effects  upon  the  nervous 
mechanism. 

Crowd-poison. — The  third  contaminant  given  to  air  from 
human  bodies  is  an  indefinite  volume  of  offensive  organic 
matter,  and  for  a  time  tliis  has  been  looked  upon  as  by 
far  the  most  harmful  part  of  animal  exhalations.     But 

1  Mitchell,  Billings,  and  Bergcy,  loc.  cit. 


CBOWD-POISON;    COMBUSTION-PRODUCTS.         83 

recently  experiments  by  various  investigators  have  seemed 
to  indicate  that  this  organic  effluvium  is  not  so  dangerous 
as  it  has  hitherto  been  considered,  and  that  part  at 
least  of  the  symptoms  due  to  air  vitiated  by  respira- 
tion is  to  be  attributed  to  the  conditions  already  men- 
tioned, viz.,  a  decrease  of  oxygen  and  an  increase  of 
carbon  dioxide,  heat,  and  moisture.  It  is  also  doubtful 
whether  much,  if  any,  of  this  organic  matter  comes  from 
the  lungs  of  healthy  persons.  "  In  ordinary  quiet  respira- 
tion no  bacteria,  epithelial  scales,  or  particles  of  dead 
tissue  are  contained  in  the  expired  air.  .  .  .  The  cause  of 
unpleasant,  musty  odors  in  rooms  may  in  part  be  due  to 
volatile  products  of  decomposition  from  decayed  teeth, 
foul  mouths,  or  disorders  of  the  digestive  apparatus,  and 
in  part  to  volatile  fatty  acids  given  off  with  or  produced 
from  the  excretions  of  the  skin,  and  from  clothing  soiled 
with  such  excretions."  ^  However,  whatever  may  be  the 
exact  source  of  this  contamination,  we  know  this  concern- 
ing it — that  it  is  decidedly  offensive  to  the  sense  of  smell, 
that  it  is  organic  and  nitrogenous,  yielding  ammonia,  dark- 
ening sulphuric  acid,  decolorizing  potassium  permanganate, 
and  rendering  obnoxious  pure  water  through  which  the 
vitiated  air  has  been  drawn.  Moreover,  it  must  in  fair- 
ness be  stated  that  in  spite  of  the  later  experiments  it  has 
seemed  to  such  careful  investigators  as  Brown-Sequard, 
d'Arsonval,  Merkel,  and  others  to  be  directly  poisonous  to 
lower  animals.  In  general,  it  is  given  off  proportionately 
with  the  carbon  dioxide  from  the  body,  though  this  rule  is 
not  infallible ;  it  is  apt  to  be  unevenly  distributed  through- 
out the  atmosphere  of  the  apartment,  and  is  probably 
therefore  not  truly  gaseous,  but  more  like  an  impalpable 
dust ;  it  oxidizes  but  slowly,  being  evident  for  some  time 

1  Mitchell,  Billings,  and  Eergey,  loc.  cit. 


84  THE  ATMOSPHERE— AIR. 

after  fresh  air  has  been  admitted  and  the  carbon  dioxide 
has  been  reduced  almost  to  the  normal,  and,  while  neither 
condensed  nor  dissolved  in  the  aqueous  vapor  from  the 
body,  it  is  especially  attracted  and  retained  by  hygroscopic 
substances  such  as  wool,  paper,  feathers,  etc.  Its  smell 
is  generally  perceptible  when  the  respirafory  carbon  dioxide 
reaches  0.03  or  0.04  per  cent.,  sometimes  before  this  point 
is  reached,  especially  in  sick-rooms  or  hospital  wards,  and 
is  decidedly  offensive  when  the  total  carbon  dioxide  ap- 
proaches 0.1  per  cent. 

The  most  important  of  the  impurities  resulting  from 
the  combustion  of  coal,  the  principal  fuel  substance  used 
in  towns  and  cities,  are  soot  and  tarry  matters  (to  the  ex- 
tent of  about  1  per  cent,  of  the  coal  consumed),  carbon 
monoxide  and  dioxide,  aqueous  vapor,  and  more  or  less 
ammonium  sulphide,  carbon  disulphide,  hydrogen  sul- 
phide, sulphur,  sulphur  dioxide,  and  sulphuric  acid.  The 
relative  amounts  of  the  oxides  of  carbon — as  M^ell  as 
of  the  other  gases — will  depend  upon  the  perfection  of 
combustion  ;  "  but  it  has  been  calculated  that  for  every 
ton  of  coal  burnt  in  London  something  like  three  tons  of 
carbon  dioxide  are  produced,"  and  as  the  coal  consump- 
tion of  that  city  is  over  30,000  tons  per  diem,  we  can 
readily  see  that  its  atmosphere  must  receive  the  enormous 
daily  contamination  of  about  300  tons  of  soot  and  90,000 
tons  of  carbonic  acid.  No  wonder  they  have  an  occa- 
sional fog  there  ! 

The  combustion-products  of  wood  are  in  the  main 
carbon  monoxide  and  dioxide,  and  water,  while  those 
of  coke  and  of  gas  are  practically  the  same  as  those  of 
coal.  From  the  heating  apparatus,  if  properly  con- 
structed and  arranged,  these  products  j)ass  almost  directly 
to  the  exterior  of  dwellings    and    arc   rapidly  dissipated 


APPARATUS  FOR  LIGHTING.  85 

in  spite  of  their  excessive  volume,  for  "  diifusion  and  the 
ever-moving  air  rapidly  purify  the  atmosphere  from  carbon 
dioxide,"  and  in  fact  from  the  other  combustion-products 
also,  with  the  exception  of  the  soot  and  tarry  products. 

Should,  however,  combustion  be  incomplete,  or  should 
the  stoves  or  other  heating  apparatus  be  inqjerfect,  the 
gases  may  seriously  or  even  dangerously  contaminate  the 
house-air,  the  deadly  carbon  monoxide  being  particularly 
liable  to  leak  not  only  through  the  crevices,  but  actually 
through  the  heated  cast-iron  plates,  etc.,  of  stoves  and 
furnaces.  Theoretically,  a  pound  of  coal  requires  160 
cubic  feet  of  air  for  its  perfect  combustion,  but  actually 
from  one-half  to  as  much  more  must  be  supplied  to  the 
ordinary  heating  apparatus  to  secure  complete  oxidation 
of  the  fuel. 

Practically  all  the  devices  for  artificial  illumination, 
with  the  exception  of  the  incandescent  electric  light,  give 
oif  directly  to  the  surrounding  air  combustion-products 
which  are  much  the  same  as  those  from  coal,  'and 
this  contamination  is  consequently  a  positive  factor  in 
the  vitiation  of  in-door  air.  "  Every  cubic  foot  of 
coal-gas  yields,  on  combustion,  roughly,  half  its  own 
volume,  or  0.52  cubic  foot,  of  carbon  dioxide,  and  1.34 
cubic  foot  of  water  vapor,"  besides  some  little  carbon 
monoxide  when  ordinary  burners  are  used.  "  Speaking 
generally,  it  may  be  said  that  each  cubic  foot  of  gas  burnt 
per  hour  from  the  ordinary  burners  vitiates  as  much  air 
as  would  be  rendered  impure  by  the  respiration  of  an  in- 
dividual ;  it  at  the  same  time  will  raise  the  temperature 
of  31,290  cubic  feet  of  air  1  degree  F.,  and  yields  217 
calories  (a  kilogramme  of  water  heated  1  degree  C.)  or  860 
British  heat-units  (a  pound  of  water  heated  1  degree  F.)."^ 
^  Notter  and  Firth,  Treatise  on  Hygiene,  p.  140. 


86 


THE  ATMOSPHERE^AIR. 


But  inasmuch  as  the  products  of  combustion  are  super- 
heated, they  rise  at  once  to  the  top  of  the  room  and,  for 
the  most  part,  quickly  escape  to  the  outer  air  through  the 
combined  influence  of  negative  gravity  and  diffusion  ;  so 
that  comparatively  little  air  is  needed  to  dilute  the  small 
proportion  of  such  products  that  eventually  cool  and  fall 
to  the  breathing-level. 

The  following  table  ^  shows  the  influence  of  various 
lighting  agents  with  respect  to  the  condition  of  the  room- 
air  : 


■3 

1  8 

1  ^ 

^  > 
S  ° 

o 

■a 
|| 

"^  3 

-a 

^  3 

3  T3 
M  ? 

"3  3 

11 
W 

o 

III 
!> 

Cu.  ft. 

Cu.  ft. 

Cn.  ft. 

Tallow  candles 

2200  grains 

16 

10.7 

7.3 

8.2 

1400 

12.0 

Sperm  candles 

1740       " 

IG 

9.6 

6.5 

6.5 

1137 

11.0 

Paraffin  oil  lamp 

992       " 

16 

6.2 

4,5 

3.5 

1030 

7.5 

Kerosene  oil  lamp 

909       " 

16 

5.9 

4.1 

3.3 

1030 

7.0 

Coal-gas,  No.  5  liatwing 

burner 

5.5  cu.  ft. 

16 

6.5 

2.8 

7.3 

1194 

5.0 

Coal-gas,  Argand  burner   .    .    . 

4.8      " 

16 

5.8 

2.6 

6,4 

1240 

4,3 

Coal-gas,     regeneration     (Sie- 

,3  2      " 

32 

50 
16 

3.6 

4.1 
0.0 

1.7 

1.8 
0.0 

4,2 

4.7 
0.0 

760 

763 
37 

2.8 

Coal-gas  (Welsbach   inrandes- 
cent)                                .... 

.3.5      " 

3.0 

Electric  incandescent  light  .    . 

0.3  lb.  coal 

0.0 

From  this  table  it  will  be  learned  that  the  incandes- 
cent electric  light  is  the  most  satisfactory  from  a  hygienic 
])oint  of  view,  and  there  is  no  doubt  that  its  very  general 
introduction  has  done  much    toward  obviatin<ij  a  constant 


'  Notter  aiifl  Firth,  Tn-iUise  on  HyRiciio,  p.  141. 


APPARATUS  FOB  LIOHTINQ.  87 

source  of  vitiation,  especially  in  rooms  which  require 
much  artificial  light,  and  are  at  the  same  time  diffi- 
cult to  ventilate.  It  is  said  that  in  a  bank  in  London, 
in  which  several  hundred  persons  are  employed,  the 
absences  on  account  of  illness  have  been  so  far  reduced, 
apparently  by  the  introduction  of  the  incandescent  electric 
light  alone,  that  the  extra  labor  gained  has  more  than 
compensated  for  the  increased  cost  of  lighting.  The 
electric  arc  light  is  said  to  form  nitric  acid ;  but  even 
so,  its  effects  are  not  so  harmful  as  are  those  of  the  prod- 
ucts of  combustion  of  the  ordinary  candle,  lamp,  or 
gas-jet. 

Next  to  the  incandescent  electric  light  in  importance 
are  the  Welsbach  and  Siemens  gas-lights ;  but  of  these  the 
latter  has  not  the  illuminating  power,  nor  is  it  so  well 
adapted  to  house  use  as  is  the  former.  The  Welsbach 
light  makes  use  of  the  Bunsen  flame  (in  which,  by  the 
way,  the  carbon  of  the  gaseous  fuel  is  completely  consumed 
and  converted  into  carbon  dioxide)  to  render  incandescent 
a  non-combustible  mantle  or  network,  composed  of  vege- 
table fibre  saturated  with  the  oxides  of  certain  metals 
which  have  the  property  of  becoming  intensely  luminous 
when  sufficiently  heated.  It  gives  a  white  light  of  great 
illuminating  and  considerable  actinic  power,  and  of  prac- 
tically unvarying  intensity.  In  fact,  this  quality  of 
steadiness,  in  which  it  surpasses  even  the  incandescent 
electric  light,  is  by  no  means  the  least  of  its  hygienic 
advantages,  since  such  steadiness  is  an  important  factor 
in  the  conservation  of  the  eyesight. 

Recently  hydrocarbon  (gasoline)  lamps,  making  use  of 
an  incandescent  mantle  similar  to  the  Welsbach,  have 
l)een  placed  on  the  market,  and  are  said  to  be  safe  and  free 
from  odor  or  danger  of  explosion.     If  these  claims  can  be 


88 


THE  ATMOSPHERE— AIR. 


sustained,  such  lamps  are  of  value,  since  they  furnish  a 
})owerfLil  and  steady  incandescent  light  at  very  low  cost. 

A  comparatively  new  illuminant,  not  mentioned  in  the 
foregoing  table,  is  acetylene  gas.  This  gives  a  very  white 
and  powerfully  actinic  light,  and,  on  account  of  ease  of 

Fig.  12. 


Chimney. 


Shade  Support. 


Mantle, 
tie  Support. 

Chimney  Support. 
Gauze  Tip. 

Gas  Spreader. 

;\l\\JJorrugated  Cap. 
iijilantle  Carrier. 
i\}^Gentrc  Tube. 

Bohesche  Support. 
Gallery. 
Buuseii  Tube. 

Air  Shutter. 


Adjustable  Chech, 
Welsbach  light. 

production  and  the  small  amount  needed  for  ordinary 
lighting,  is  cliea])  and  does  not  greatly  vitiate  the  atmos- 
phere. But  a  mixture  of  the  nnburned  acetylene  witii  air 
in  proportions  of  from  4  to  25  per  cent,  is  highly  explosive, 
and  consequently  the  gas  is  not  yet  much  used  for  interior 
lighting. 


SEWER-OAS  AND  SOIL-AIR.  89 

Sewer-gas  and  Soil-air. — What  is  commonly  called 
sewer-gas  is  a  mixture  of  a  number  of  gases,  such  as  car- 
bon dioxide,  carburetted  hydrogen,  ammonium  and  hydro- 
gen sulphide,  nitrogen,  etc,  together  with  a  considerable 
amount  of  fetid  organic  matters,  the  volatile  or  semi- 
volatile  products  of  animal  and  vegetable  decomposition, 
varying  according  to  the  condition  of  the  sewer,  the 
kind  of  matter  received  therein,  the  amount  of  surface- 
water,  etc.  The  air  from  a  closed  cesspool  may  be  ex- 
tremely foul  and  poisonous,  so  much  so  that  the  emana- 
tions have  not  infrequently  caused  death  in  those  who 
inhaled  them  in  full  concentration  ;  on  the  other  hand,  the 
atmosphere  of  a  properly  constructed  and  well-flushed 
sewer  may  be  almost  as  pure  as  that  above  the  surface  of 
the  ground.  Bacteria  are  present  in  varying  numbers, 
with  the  possibility  of  some  of  them  being  the  germs  of 
specific  diseases.  But  fresh  sewage  is  not  so  likely  to 
contaminate  the  air  above  it  with  microbes  as  that  in 
which  decomposition  has  begun,  since  Frankland  has 
shown  that  solid  or  liquid  particles  are  not  liable  to  be 
scattered  into  the  air  by  any  disturbance  to  which  the 
sewage  may  be  subjected  until  gases  of  decomposition 
are  produced.  According  to  some  writers,  the  bursting 
of  bubbles  of  gas  on  the  surface  may  discharge  the  bac- 
teria into  the  sewer-air.  It  has  also  been  shown  that 
"  bacteria  can  undoubtedly  grow  up  the  sides  or  walls  of 
damp,  nutrient  sewers,  and  if . these  latter  become  at  all 
dry,  air  currents  readily  detach  and  disperse  them."  It 
is,  however,  questionable  whether  many  disease  germs  can 
withstand  the  natural  antagonism  of  the  saprophytic  bac- 
teria that  predominate  in  sewage  and  on  sewer  walls. 

Another  class  of  impurities  that  may  at  times  be  found 
in  the  air  of  dwellings  comprises  those  coming  from  the 


90 


THE  ATMOSPHERE— AIR. 


soil  and  soil-air.  The  soil,  in  hygiene,  refers  to  all  that 
portion  of  the  earth's  crust  that  can  in  any  way  aifect  the 
health.  All  soils  contain  more  or  less  air — soft  sandstones 
from  20  to  40  per  cent.,  loose  vsand  from  40  to  50  per 
cent.,  and  loose  soils  often  verv  much  more. 


Fig.  14. 


ittikSM 


.,r>o 


rvf^- 


A]>p!iratus  for  determination  of  f'Oo  in  soil  air.    (TlARRiNfiTON.) 

As  the  soil  is  tlio  recipient  of  most  of  the  solid  and 
liquid  waste  of  all  animal  and  vetxetal)l(^  life,  and  as  the 
myriads  of  sa])ro])hytic  hacteria  that  inhabit  its  upper 
strata  arc  <'onstaiitl\-  workinor;  to  convert  this  dead  orranic 


COMPOSITION  OF  SOIL-AIB.  91 

matter  into  simpler  compounds  suited  to  the  nourishment 
of  plant-life,  the  soil-air,  taking  the  atmosphere  above  as 
a  standard,  will  usually  be  far  from  jDure.^  It  is  rich  in 
carbon  dioxide  and  in  organic  vapors  and  gases,  while  the 
proportion  of  oxygen  is  probably  always  less  than  that  of 
the  air  above  ground.  Moreover,  the  carbon  dioxide  in- 
creases and  the  oxygen  decreases  the  deeper  below  the 
surface  the  sample  is  taken.  As  much  of  the  carbon  di- 
oxide is  evidently  derived  from  organic  pollutions,  it  might 
be  supposed  that  this  gas  could  be  taken  as  an  index  of 
the  degree  of  the  latter,  and  so  it  might  if  other  conditions, 
such  as  permeability  of  soil,  rate  of  circulation,  etc.,  were 
always  the  same.  But  they  are  not,  and  the  composition 
of  the  soil-air  is  practically  not  the  same  at  any  two  places, 
nor  for  the  same  place  at  different  times.  The  under- 
ground air  is  constantly  in  circulation,  even  to  a  consider- 
able depth ;  but  there  is  a  hindrance  to  its  free  movement 
and  diifusibility,  and  this,  together  with  the  great  variation 
in  the  distribution  of  oxidizable  and  other  contaminating 
matters,  causes  the  variations  in  its  composition.  The 
carbon  dioxide,  therefore,  cannot  be  taken  as  an  index 
of  the  relative  purity. 

The  forces  that  maintain  the  circulation  of  the  ground- 
air  are  the  wind,  the  daily  change  of  surface  temperature, 
the  fall  of  rain,  and  especially  in  winter  the  local  and  arti- 
ficial conditions  of  civilization.  A  very  slight  wind  will 
drive  air  through  the  soil  for  long  distances,  the  rise  and 
fall  of  the  ground-water  has  its  obvious  effect,  and  the 
movement  due  even  to  slight  changes  of  temperature  is 
likely  to  be  quite  extensive  and  positive. 

1  Too  much  importance  cannot  be  attributed  to  this  saprophytic  action 
in  the  upper  soil,  for  it  is  one  of  nature's  wonclerful  methods  of  securing 
and  conserving  not  only  the  purity  of  our  environment,  but  also  the 
perpetuation  of  organic  life. 


92  THE  ATMOSPHERE— AIR. 

Owing  to  evaporation  from  the  ground-water,  the  soil- 
air  is  always  quite  humid,  and,  according  to  some  writers, 
may  also  be  laden  with  bacteria  and  other  very  light 
substances  lifted  up  by  the  ascensional  power  of  evapo- 
ration. 

As  sewage,  house-wastes,  and  dirt  of  all  kinds  are  par- 
ticularly liable  to  contaminate  the  soil  about  any  inhabited 
dwelling,  the  air  of  that  soil  will  more  than  likely  be 
very  impure,  and  care  must  be  taken  that  it  is  not  drawn 
into  the  house.  This  is  especially  apt  to  happen  in  cold 
weather,  when  house-fires  are  lighted  and  the  in-door  air  /^  /. 
is  thus  made  warmer  than  that  without,  the  tendency  then 
being  for  the  soil-air  to  pass,  if  possible,  through  the  cellar 
walls  and  floors.  These  should  be  made  as  nearly  air-tight 
as  possible,  and  special  attention  should  be  given  to  the 
space  underneath  and  about  the  furnaces  or  basement 
heating  apparatus.  As  an  instance  of  the  importance  of 
these  precautions,  Hime  ^  gives  an  account  of  the  death 
of  four  persons.  Enough  illuminating-  (coal-)  gas  was 
drawn  from  a  broken  pipe  fifteen  feet  distant  from'  the 
foundation  walls  of  the  dwelling  to  cause  the  fatality,  al- 
though there  were  only  eight  or  ten  inches  of  tramped 
earth  above  the  pipe  and  the  only  aspirating  force  was  the 
dillerence  of  temperature  within  and  witliout  the  house. 
A  number  of  explosions  have  occurred  due  to  a  similar 
leakage  of  gas  from  street  mains  through  basement  walls 
or  into  drains  and  sewers,  since  the  admixture  of  illumi- 
nating-gas with  air  forms  a  most  powerful  and  dangerous 
explosive. 

There  is  no  direct  evidence  that  the  emanations  from 
bone-yards,  soap-factories,  garbage-incinerators,  etc.,  are 
actually  harmful  to  health  ;  l)ut  they  may  be  very  decided 

'  Stevenson  and  Muri)h,v,  Treatise  on  Hygiene,  vol.  i.,  p.  949. 


DISEASES  DUE  TO  IMPURE  AIR.  93 

nuisances  to  those  living  near  by,  and  all  such  places 
should  be  strictly  controlled  by  the  proper  sanitary 
authorities. 

The  atmosphere  of  mines  and  other  excavations  is  sub- 
ject to  contamination  by  the  excess  of  carbon  dioxide  in 
the  soil-air,  by  gases  from  blasting  agents  and  from  fis- 
sures in  rock,  and  by  the  products  of  respiration  from 
men  and  animals  working  in  the  mines,  etc.  The  air  in 
the  holds  of  ships  is  also  likely  to  be  foul  owing  to  the 
difficulty  of  changing  it  sufficiently  often,  and  frequently 
also  to  the  insanitary  character  of  cargoes.  In  such  situa- 
tions proper  ventilation  should  be  secured  by  all,  means 
available,  and  special  care  taken  that  the  impure  air  does 
n(jt  affect  the  laborers  in  the  one  case  or  the  passengers 
and  crew  in  the  other. 

Diseases  Caused,  by  Impure  Air. — As  a  rule,  the 
human  system  has  the  power  of  accommodating  itself, 
through  habit,  to  withstand  influences  which,  in  one 
unaccustomed  to  them,  would  soon  produce  serious  re- 
sults. But  in  spite  of  this,  if  the  body  be  exposed  for 
any  considerable  length  of  time  to  conditions  of  impurity 
or  deterioration  in  its  supply  of  air,  water,  or  food,  such 
conditions  will  always  tend  to  undermine  health  and 
increase  the  susceptibility  to  disease,  even  though  they 
cause  no  more  serious  results.  "  Statistical  inquiries  on 
mortality  prove  beyond  a  doubt  that  of  the  causes  of 
death  which  are  usually  in  action,  impurity  of  the  air  is 
most  important.  No  one  who  has  paid  any  attention  to 
the  condition  of  health  and  the  recovery  from  disease  of 
those  persons  who  fall  under  his  observation,  can  doubt 
that  impurity  of  the  air  marvellously  affects  the  first,  and 
influences  and  sometimes  even  regulates  the  second. 
.     .     .     The  air  may  affect  health  by  variations  in  the 


94  THE  ATMOSPHERE — AIR. 

amount  or  conditions  of  its  normal  constituents,  by  dif- 
ferences in  physical  properties,  or  by  the  presence  of 
impurities.  While  the  immense  effect  of  impure  air  can- 
not be  for  a  moment  doubted,  it  is  not  always  easy  to 
assign  to  each  impurity  its  definite  action.  The  evidences 
of  injury  to  health  from  impure  air  are  found  in  a  larger 
proportion  of  ill  health — /.  e.,  of  days  lost  from  sickness 
in  the  year — than  under  other  circumstances  ;  an  increase 
in  the  severity  of  many  diseases,  which,  though  not 
caused,  are  influenced  by  impure  air,  and  a  higher  rate 
of  mortality,  especially  among  children,  whose  delicate 
frames  always  give  us  the  best  test  of  food  and  air."  ^ 

The  definite  diseases  caused  by  the  solid  impurities 
in  the  atmosphere  are  almost  all  such  as  afPect  the 
respiratory  passages  and  organs,  with  the  possible  excep- 
tion of  those  engendered  by  specific  bacteria  and  other 
microbes.  Much  therefore  depends  upon  the  physical 
character  of  the  solid  impurities.  Soft  particles  and  those 
with  edges  smooth  and  rounded,  like  soot  and  coal-dust, 
may  apparently  do  nothing  more  than  coat  or  clog  the 
air-vesicles  and  finer  bronchial  tubes,  and  in  this  way  di- 
minish the  area  of  lung  tissue  exposed  to  the  inspired  air, 
ahliough  it  is  questionable  whether  any  foreign  matter  in 
the  lur.&s  does  not  cause  more  or  less  irritation.  With 
most  of  us,  however,  such  impurities  are  of  little  account  if 
care  be  taken  to  develop  the  full  respiratory  capacity  of  the 
chest;  but  where  the  air  is  heavily  charged  with  such  dust 
it  has  a  positive  eifect  upon  health  and  duration  of  life. 
In  1862  Sir  John  Simon  stated  that  with  one  exception 
"  the  300,000  (coal)  miners  of  England  and  Wales  break 
down  as  a  class  prematurely  from  broncliitis  and  pneu- 
monia, caused  by  the  atmosphere  in  which  they  live.  The 
'Stevenson  and  Murphy,  vol.  i.,  pp.  121  and  122. 


EFFECT  OF  DUSTS  IN  AIR.  95 

exception  is  important.  The  colliers  of  Durham  and 
Northumberland,  where  the  mines  are  well  ventilated,  do 
not  appear  to  suffer  from  an  excess  of  pulmonary  diseases, 
or  do  so  in  a  slight  degree  only."  Happily,  since  this  was 
written  satisfactory  ventilation  systems  have  been  placed  in 
most  of  the  collieries  of  England,  and  the  condition  of  the 
laborers  correspondingly  improved ;  but  coal-miners  are 
still,  as  a  class,  particularly  liable  to  bronchitis,  pneu- 
monia, asthma,  emphysema,  and  fibrosis  (fibroid  phthisis), 
though  they  seem  to  be  but  slightly  subject  to  primary 
tuberculosis  of  the  lungs  or  other  organs. 

On  the  other  hand,  if  the  particles  of  dust  in  the  air 
are  hard,  angular,  and  sharp,  the  lung  tissues  are  readily 
lacerated,  inflammatory  processes  are  quickly  set  up,  and 
the  opportunity  for  the  inoculation  of  tubercle  bacilli  and 
other  disease  germs  is  very  great.  The  mortality  from 
tubercular  phthisis  among  metal-miners,  needle-cutters, 
steel-grinders  and  tool-grinders,  cotton-spinners,  etc.,  is 
remarkable,  and  they  are  also  especially  subject  to  asthma 
and  emphysema.  Among  Cornish  tin-miners,  68  per  centj_ 
of  all  sick  are  consumptive ;  of  needle-makers,  over  60 
per  cent.;  of  flint-cutters,  glass-cutters  and  -polishers,  and 
of  grindstone-makers,  from  80  to  90  per  cent.,  etc.  It 
is  said  that  a  mixture  of  mineral  and  metallic  dust  seems 
to  be  more  harmful  than  metallic  dust  alone,  perhaps 
because  of  the  greater  clogging  of  the  air-vesicles  by  the 
mineral  matter. 

Likewise,  with  other  occupations  where  there  is  much 
irritative  dust  floating  in  the  air,  the  effect  upon  the 
health  of  the  worker  is  marked,  and  we  find  lung  troubles 
prevalent  and  many  suffering  and  dying  from  phthisis, 
as,  for  instance,  among  cotton-spinners,  flax-dressers, 
hemp-dressers,   pottery- makers,    etc.      Defective  ventila- 


96  THE  ATMOSPHERE^AIR. 

tion,  accumulations  of  noxious  gases,  improper  habits, 
insufficient  disinfection  of  sputa,  and  often  the  excessive 
humidity  of  the  air  necessary  in  some  of  these  pursuits, 
have  doubtless  something  to  do  with  the  high  sick-rates 
and  death-rates  ;  but  withal,  the  marked  effect  of  the  solid 
atmospheric  impurities  cannot  be  denied. 

Again,  workers  in  poisonous  metals,  compounds,  or 
gases,  such  as  paint-makers  and  painters,  type-setters, 
gilders  (using  mercury),  brass-founders,  coppersmiths, 
etc.,  are  subject  to  the  influence  of  the  respective  poisons 
and  the  symptoms  produced  by  them,  with  a  correspond- 
ingly increased  mortality. 

Among  the  diseases  that  may  be  caused  by  the  inhala- 
tion or  swallowing  of  specific  micro-organisms  floating  in 
the  atmosphere  are  erysipelas,  measles,  scarlet  fever,  diph- 
theria, whooping-cough,  infectious  pneumonia,  phthisis  and 
otlier  forms  of  tuberculosis,  and  very  probably  epidemic 
influenza ;  and  although  the  germs  of  cholera  and  typhoid 
fever  are  usually  carried  by  the  drinking-water  or  food, 
they  doubtless  do  sometimes  find  their  way  into  the  sys- 
tem from  a  contaminated  atmosphere.^  Malaria  also  is 
now  practically  proved  to  be  due  to  a  minute  organism, 
which,  though  usually  introduced  into  the  human  body  in 
another  way,  may  possibly  be  present  in  the  air  of  mala- 
rial districts  and  be  carried  long  distances  thence  by  winds. 

Lastly,  the  spores  of  certain  fungi  which  have  been 
found  in  the  air  of  hospitals  and  elsewhere  are  known  to 
cause  skin  diseases,  such  as  the  tineas  and  favus  in  men  ; 
and  it  is  almost  as  certain  that  the  irritating  or  poisonous 

^The  report  of  the  commission  appointed  to  inquire  into  the  preva- 
lence and  causes  of  typhoid  fever  in  the  late  Spanish- American  War  shows 
that  in  some  cases  infection  was  probably  due  to  tlie  dust  in  the  atmos- 
phere which  had  been  raised  by  many  passing  feet  from  the  roads  over 
which  leaking  sewage  wagons  had  been  hauled. 


EFFECTS   OF  HUMAN  EXHALATIONS.  97 

pollen  of  certain  grasses  and  other  plants  have  much  to 
do  with  the  causation  or  aggravation  of  maladies  such  as 
hay-fever  or  rose-cold. 

From  what  has  been  said,  it  will  be  surmised  that 
it  is  scarcely  possible  at  present  to  specify  the  exact  eifect 
upon  the  health  of  each  of  the  impurities  given  to  the 
air  by  the  human  body,  and  that  the  symptoms  observed 
to  be  due  to  air  thus  vitiated  are  very  probably  an  evi- 
dence and  result  of  the  combined  action  of  these  factors 
rather  than  of  any  one  of  them  singly.  However,  the 
writer  feels  that  the  oppression  so  commonly  experienced 
is  often  fairly  attributable  to  the  increase  in  the  tempera- 
ture and  humidity  ;  that  the  headache,  disturbed  nutrition, 
and  febrile  condition,  lasting  for  hours  and  sometimes 
days  after  exposure  to  air  thus  vitiated,  are  either  eifects 
of  the  organic  matter  acting  as  a  poisonous  waste  when 
taken  back  again  into  the  system,  or  results  of  the  sup- 
pression of  cutaneous  excretion  dependent  upon  the  high 
content  of  moisture  in  the  air ;  and  that  the  respiratory 
carbon  dioxide  by  itself  can  but  rarely  have  much  influ- 
ence upon  comfort  or  health. 

If  the  respiratory  and  cutaneous  vitiation  be  sufficient 
to  produce  acute  eifects,  the  immediate  symptoms  will  be 
discomfort  and  a  sense  of  oppression,  followed  by  head- 
ache and  not  rarely  nausea  and  a  rather  decided  rise  of 
temperature,  all  of  which  may  last  for  some  time  even 
after  the  individual  goes  into  perfectly  pure  air.  Those 
who  habitually  live  in  such  an  atmosphere  are  almost  uni- 
formly languid,  pallid,  and  anaemic,  subject  to  headaches, 
nausea,  and  loss  of  appetite,  and  often  to  skin  disorders, 
and  are  undoubtedly  markedly  predisposed  to  phthisis, 
pneumonia,  bronchitis,  scrofula,  rhachitis,  etc.  Moreover, 
such  an  atmosphere  apparently  favors  the  rapid  spread, 
7 


98  THE  ATMOSPHEEE^AIR. 

increases  the  severity  of  and  retards  the  convalescence 
from  such  diseases  as  diphtheria,  scarlet  fever,  measles, 
typhus,  smallpox,  etc.  This  may  be  due  either  to  the 
accumulation  or  to  the  actual  multiplication  by  growth 
of  the  disease  germs  in  the  foul  air,  or  to  the  vitiated 
atmosphere  causing  a  decrease  of  bodily  resistance  and  an 
increase  in  predisposition  to  such  maladies. 

When  the  proportion  of  impurities  is  very  great,  the 
results  may  be  serious  and  even  fatal,  as  in  the  Avell- 
known  cases  of  the  ''  Bla,ck  Hole  of  Calcutta " ;  of  the 
prison  in  which  300  captives  of  war  were  crowded  after 
the  battle  of  Austerlitz  (260  dying  very  soon  after  being 
placed  therein);  and  of  the  steamer  "  Londonderry,"  in 
which,  of  200  steerage  passengers  who  were  temporarily 
crowded  into  a  cabin  (18X11X7  feet)  during  a  storm  of 
only  a  few  hours'  duration,  72  were  dead  and  others  dying 
when  the  cabin  was  opened  :  but  in  these  instances  the 
lack  of  oxygen  may  have  also  been  a  very  important  factor 
in  the  results. 

As  regards  the  influence  of  combustion-products  on 
health,  it  will  suffice  to  detail  the  symptoms  resulting 
from  inhalation  of  the  various  gases.  It  will  be  difficult 
to  show  that  these  gases,  together  with  the  coincident  soot, 
have  any  general  effect  upon  health  when  escaping  into  the 
out-door  atmosphere,  even  when  produced  in  such  enor- 
mous quantities  in  cities  as  has  been  already  indicated. 
It  is  possible  that  the  sulphur  dioxide  and  other  sulphur 
gases  might  predispose  to  or  aggravate  attacks  of  bron- 
chitis or  asthma  in  tliose  living  in  the  vi(^inity  of  gas- 
works, chemical  factories,  etc.,  l)ut  too  little  comes  from 
the  chimneys  of  dwelling-houses  to  do  niucii,  if  any,  harm. 

In-doors  the  case  is  (Hflerent,  for  the  gases  from  lights 
and  firas  become  more  and  more  concentrated  as  the  ven- 


INFLUENCE  OF  COMBUSTION-PRODUCTS.         99 

tilation  is  insufficient.  The  possible  effects  of  varying 
percentages  of  carbon  dioxide  have  been  noted.  We  have 
no  evidence  of  cases  of  chronic  poisoning  by  this  gas, 
although,  as  Parkes  says  :  "  The  presence  of  a  very  large 
amount  of  CO2  in  the  air  may  lessen  its  elimination  from 
the  lungs,  and  thus  retain  the  gas  in  the  blood,  and  thus  in 
time  possibly  produce  serious  alterations  in  nutrition." 

In  cases  of  acute  poisoning  by  this  gas — i.  e.,  where  it 
is  in  great  excess  in  the  atmosphere — there  is  an  almost 
immediate  loss  of  muscular  power,  and  the  person  may 
consequently  be  unable  to  remove  himself  from  the  place 
of  danger,  while  others  who  go  to  help  him  may  also  suc- 
cumb and  more  than  one  be  asphyxiated.  Accordhigly, 
volunteer  rescuers  should  always  remember  to  act  with 
coolness  and  great  rapidity,  and  to  provide  means  for  the 
prompt  removal  not  only  of  the  ones  they  would  save,  but 
of  themselves  as  well.  Fortunately,  when  one  who  has 
been  overcome  by  carbon  dioxide  is  brought  into  an  atmos- 
phere of  pure  air  before  life  is  extinct  and  is  aided  by 
artificial  respiration,  he  usually  recovers  quickly  and  com- 
pletely because  of  the  rapid  escape  of  the  excess  of  the 
gas  from  the  blood  and  its  replacement  by  the  necessary 
oxygen.  Death  from  carbon  dioxide  poisoning  is  prob- 
ably mainly  due  to  asphyxia,  partly  from  lack  of  oxygen 
and  partly  from  paralysis  of  the  respiratory  muscles,  of 
which  the  latter,  as  well  as  the  general  motor  palsy,  would 
seem  to  indicate  that  the  gas  itself  had  also  a  positive 
physiologic  and  toxic  effect  upon  the  nerve-centres. 

Cases  of  poisoning  by  carbon  monoxide  are  much  more 
serious.  Recovery  from  its  effects  is  slow  and  uncertain, 
because  this  gas  unites  with  the  haemoglobin  of  the  red 
blood-corpuscles,  paralyzing  them  as  it  were,  and  render- 
ing them  unable  longer  to  act  as  oxygen-carriers  to  the 


100  THE   ATMOSPHERE— AIR. 

tissues  ;  while  the  union  of  carbon  dioxide  with  the  blood 
is  always  a  much  more  unstable  one  and  readily  dissolved 
as  soon  as  interchange  with,  a  normal  atmosphere  is  avail- 
able. Less  than  0.5  per  cent,  of  carbon  monoxide  in  the  air 
has  caused  symptoms  of  poisoning,  and  more  than  2  or  3  per 
cent,  is  fatal  to  animals.  "  It  appears  that  the  gas,  volume 
for  volume,  completely  replaces  the  oxygen  in  the  blood, 
and  cannot  again  be  displaced  by  oxygen,  so  that  the  per- 
son dies  asphyxiated ;  but  Pokrowsky  has  shown  that  it 
may  be  gradually  converted  into  carbon  dioxide  and  be 
got  rid  of." 

The  symptoms  of  carbonous  oxide  (monoxide)  poisoning 
are  feebleness,  oppressed  breathing,  trembling,  and  ina- 
bility to  swallow  ;  then  "  loss  of  consciousness,  destruction 
of  reflex  action,  and  finally  paralysis  of  the  heart."  "  Hirt 
says  that  at  high  temperatures  (25°  to  32°  C.  =  77°  to 
90°  F.)  it  produces  convulsions,  but  not  at  low  tempera- 
tures (8°  to  12°  C.=:46°  to  54°  F.)."  The  blood  and 
muscles  are  made  a  brilliant  red  by  this  gas ;  darkened  by 
carbon  dioxide.  Claude  Bernard  says  that  a  mixture  of 
these  gases  is  more  destructive  than  either  separately, 
probably  because  the  excess  of  the  acid  gas  interferes 
with  conversion  of  the  monoxide  to  the  dioxide  in  the 
blood,  as  was  shown  by  Pokrowsky. 

Illuminating-  or  coal-gas — composed  of  hydrogen,  light 
and  heavy  carburetted  hydrogens,  a  little  nitrogen,  and 
carbon  dioxide,  and  from  5  to  7  per  cent.,  or  even  more, 
of  carbon  monoxide — rapidly  causes,  when  inhaled,  giddi- 
ness, hcadaclie,  nausea  and  vomiting  (occasionally),  confu- 
sion of  intellect,  loss  of  consciousness,  general  weakness 
and  depression,  partial  paralysis,  eonvnlsions,  and  the  usual 
symptoms  of  asphyxia.  Mixed  in  large  proportions  with 
the  air,  death  may  ensue  comparatively  quickly,  probably 


EFFECTS  OF  ILLUMINATING   GAS.  101 

because  of  the  large  content  of  carbon  monoxide.  It  is 
well  to  remember  that  the  so-called  water-gas,  now  so 
extensively  manufactured  for  fuel  purposes  and  also  for 
diluting  coal-gas,  contains  a  much  larger  percentage  of 
carbon  monoxide  (sometimes  from  30  to  40  per  cent.) 
than  coal-gas,  and  that  the  eifects  resulting  from  inhala- 
tion of  a  mixture  of  the  two  will  in  all  likelihood  be 
more  marked,  more  rapid,  and  more  deadly  than  with 
undiluted  coal-gas. 

"  The  effects  of  constantly  inhaling  the  products  of  gas 
combustion  may  be  seen  in  the  case  of  workmen  whose 
shops  are  dark  and  who  are  compelled  to  burn  gas  during 
a  large  part  of  the  day ;  the  pallor,  or  even  ansemia  and 
general  want  of  tone,  which  such  men  show,  are  owing 
to  the  constant  inhalation  of  an  atmosphere  so  impure." 

Sulphurous  acid  gas  (SO2)  and  hydrogen  sulphide  (HgS) 
are  each  fatal  to  life,  the  latter  when  in  a  compara- 
tively concentrated  state ;  but  they  are  offensive  to  the 
senses  and  thus  give  warning  of  their  presence,  so  that 
there  is  less  danger  of  their  causing  serious  results.  Men 
can  accustom  themselves  to  much  larger  proportions  of 
hydrogen  sulphide  in  the  atmosphere  than  can  animals, 
but  continued  exposure  to  it  is  liable  to  give  rise  to  ver- 
tigo, headache,  slow  and  weak  pulse,  sweating,  and  loss 
of  strength. 

When  sewer-gas  or  soil-air  escapes  into  the  outer  air 
they  are  usually  soon  diluted  beyond  power  for  harm ; 
but  if  either  gains  access  to  closed  rooms  or  unventilated 
dwellings,  its  effects  upon  the  inmates  are  depressing  and 
decidedly  harmful.  In  either  case,  concentration  of  the 
impurities  may  cause  acute  symptoms,  such  as  vomiting, 
purging,  severe  hea<:lache  and  prostration ;  aad  either 
soil-air  or  sewer-gas  may  possibly  at  times  carry  the  germs 
of  infectious  diseases.    Their  influence,  however,  is  usually 


102  THE  ATMOSPHERE^ AIR. 

insidious,  owing  to  dilution  with  the  house-air ;  and  the 
more  common  symptoms  wnll  probably  be  pallor,  languor, 
frequent  headache,  loss  of  appetite,  diarrhoea,  impaired 
health,  and  often  chronic  ansemia.  Children  especially 
suffer  in  nutrition,  and  with  them  febrile  attacks  may  be 
frequent ;  but  with  all,  the  power  of  resisting  such  dis- 
eases as  typhoid  fever,  diphtheria,  etc,  is  lessened  and  the 
susceptibility  to  them  is  increased,  the  sickness  more  severe, 
and  the  convalescence  more  prolonged.  Indeed,  sewer-gas 
and  soil-air  probably  aggravate  all  diseases. 

In  this  connection  Alessi  has  shown  that  when  small 
animals,  such  as  rabbits,  rats,  and  guinea-pigs,  have  been 
exposed  to  sewer-air  for  some  days,  by  far  the  larger 
majority  when  inoculated  with  only  a  small  quantity  of 
a  slightly  virulent  typhoid  culture  contract  the  disease  and 
die,  while  almost  none  succumb  of  those  treated  similarly 
in  every  way  excepting  by  the  exposure  to  sewer-air.  He 
also  showed  that  the  inoculations  were  more  deadly  when 
the  previous  exposure  to  the  noxious  gas  had  been  less 
than  two  weeks  than  when  it  exceeded  that  period,  indi- 
cating that  animals,  as  well  as  persons  accustomed  to  such 
contamination,  are  not  apt  to  manifest  the  symptoms  due  to 
it  so  rapidly  or  so  seriously  as  are  those  who  experience  it 
for  the  first  time — a  fact  well  known  to  all  observers.  It 
is  only  fair  to  say  that  these  experiments  of  Alessi  have 
apparently  been  controverted  by  other  observers ;  but, 
whichever  may  be  correct,  the  truth  of  the  following 
quotation  doubtless  still  holds  good  : 

^'  There  is  undoubtedly  a  poisonous  agency  at  work 
when  sewer-gas  is  inhaled,  which,  though  it  may  not 
directly  act,  yet  so  prepares  the  soil  that  the  system  is 
unable  to  resist  the  invading  (organism  when  it  comes."  ^ 

'  Notter  and  Firth,  p.  159. 


CHAPTER    IV. 

VENTILATION  AND  HEATING. 

As  we  are  not  usually  able  to  destroy  the  impurities 
of  the  atmosphere  within  our  dwellings  as  fast  as  they 
are  produced,  we  have  recourse  to  ventilation  as  a  means 
for  their  dilution  and  prompt  removal.  We  must  not 
think,  however,  that  we  do  all  that  is  necessary  if  we  only 
renew  the  in-door  air,  for  unless  the  source  and  supply 
from  which  we  take  that  which  is  to  replace  or  dilute  the 
vitiated  air  be  pure  and  clean,  any  system  of  ventilation 
which  we  may  adopt  will  be  of  little  value. 

External  ventilation  of  buildings,  streets,  and  cities 
is  of  importance,  then,  as  well  as  that  which  relates  only 
to  the  interior  of  dwellings,  workshops,  and  places  of 
assembly.  Numerous  investigations  and  statistics,  both 
here  and  abroad,  show  that  "  the  health  of  a  town  largely 
depends  upon  the  width  of  the  streets,  the  general  height 
of  the  buildings,  and  the  amount  of  yard-space  at  the  rear 
of  each  which  separates  it  from  its  opposite  neighbor." 
It  is  also  difficult  to  overestimate  the  value  of  wide  streets, 
numerous  diagonal  ones  and  frequent  parks  or  open  spaces, 
especially  in  the  more  thickly  inhabited  portions  of  a  city. 
In  this  connection  we  may  refer  with  advantage  to  some 
work  of  Dr.  H.  S.  Anders,  of  Philadelphia,  in  which  he 
shows  that  "the  number  of  deaths  from  phthisis  on  a  very 
wide  street  is  proportionately  small  compared  with  those  on 
almost  any  one  narrow  street,"  and  "  that  there  is  plainly 

103 


104  VENTILATING   AND  HEATING. 

and  generally  a  high  mortality-rate  from  consumption 
associated  with  street  narrowness  in  not  a  small  part  of 
-Philadelphia,  and  that  the  relation  between  a  high  mor- 
tality and  narrow  streets  is  a  positive  and  vital  one." 
His  statistics,  covering  a  period  of  fifteen  years,  show  tliat 
in  one  city  ward,  certainly  favored  as  to  location,  the 
ratio  of  deaths  from  phthisis  per  square  or  block  on  streets 
over  to  those  on  streets  under  forty  feet  in  width  was 
approximately  as  3  is  to  5. 

As  regards  internal  ventilation,  it  will  be  well  to  deter- 
mine at  the  outset  the  meaning  and  limitations  of  the 
term.  Parkes  says  :  "  It  will  be  desirable  to  restrict  the 
term  ventilation  to  the  removal  or  dilution,  by  a  supply 
of  pure  air,  of  the  pulmonary  and  cutaneous  exhalations 
of  men,  and  of  the  products  of  combustion  of  lights  in 
ordinary  dwellings,  to  which  must  be  added,  in  hospitals, 
the  additional  effluvia  which  proceed  from  the  persons 
and  discharges  of  the  sick.  All  other  causes  of  impurity 
of  air  ought  to  be  excluded  by  cleanliness,  proper  removal 
of  solid  or  liquid  excreta,  and  attention  to  the  conditions 
surrounding  dwellings."  With  the  function  of  ventilation 
thus  limited,  it  will  not  be  necessary  to  make  provision 
for  such  an  abundant  supply  of  pure  air  as  might  other- 
wise seem  advisable.  It  is  evident  also  that  the  purity 
of  in-door  air  must  almost  always  be  relative  and  not 
absolute,  especially  in  a  climate  like  ours,  which  for  a 
considerable  portion  of  the  year  necessitates  warming  of 
the  air  and  some  consequent  economy  in  its  use. 

It  seems  strange  that  attention  has  not  been  given  to 
the  possibility  of  purifying  a  vitiated  atmosphere  by  means 
of  fire  rather  than  by  the  removal  or  dilution  of  the  im- 
purities, especially  as  we  so  often  employ  heat  as  an  agent 
to  destroy  or  alter  the  harmful  qualities  of  other  substances 


FACTORS  IX    YENTILATISG   PROBLEMS.         105 

intimately  coucerued  with  our  welfare.  The  objection 
that  many  would  offer  at  first  thought  to  such  a  plan  is 
that  fire  would  rob  the  air  of  all  or  most  of  its  oxygen, 
but  a  little  calculation  and  consideration  will  show  that 
this  is  by  no  means  a  necessary  result,  and  that  a  proper 
apparatus  might  actually  consume  but  comparatively  little 
of  this  gas  and  give  off  but  little  carbon  dioxide  as  a  com- 
bustion-product to  the  atmosphere.  So  far  as  the  writer 
knows,  but  one  device  on  the  market  has  this  function 
professedly  embodied  in  it,  and  it  apparently  does  what  is 
claimed  for  it  in  this  respect.  The  possibilities  of  the 
suggestion  invite  ftirther  investigation. 

To  discover  the  quantity  of  air  desirable  and  consistent 
with  the  requirements  of  good  ventilation  and  the  main- 
tenance of  health,  two  factors  must  be  determined  :  (a) 
the  extent  to  which  the  air  of  a  room  is  contaminated  in 
a  given  time  by  the  impurity  it  receives,  and  (6)  the 
limit  of  permissible  impurity  beyond  which  there  will  be  a 
possible  risk  or  detriment  to  health.  In  accordance  with 
the  above-mentioned  limitations  of  Parkes,  the  contamin- 
ating substances  will  usually  be  comparatively  few  in 
number,  but  the  same  factors  are  to  be  sought  in  the  case 
of  any  detrimental  substances  in  the  atmosphere  at  any 
time,  provided  their  source  or  cause  cannot  be  directly 
removed. 

Although  it  is  extremely  difficult  to  determine  quanti- 
tatively the  organic  matter  given  off  by  human  exhala- 
tion in  any  given  time,  the  carbon  dioxide,  as  has  been 
stated,  is  usually  exhaled  in  a  reasonably  constant  ratio 
with  it,  and  can  therefore  be  used  as  an  index  of  the 
amount  of  it  contaminating  the  air.  Taking  Pettenkofer's 
figures,  which  have  been  substantially  confirmed  by  other 
investigators,  viz.,  0.6  cubic  foot  of  carbon  dioxide  per 


106  VEXTILATIOX  AXD   HEATING. 

hour  per  head  for  a  mixed  assemblage  at  rest,  0.7  cubic 
foot  for  adult  males,  and  increasing  amounts  according 
to  the  physical  work  done,  we  have  the  first  factor  (a)  of 
our  problem  determined  for  all  cases  where  the  products 
of  human  respiration  and  exhalation  are  the  only  contam- 
inants. 

In  establishing  the  limit  of  permissible  impurity — the 
second  factor  (6j — it  will  naturally  be  advisable  to  require 
that  the  supply  of  air  from  without  shall  be  sufficient  not 
only  to  be  thoroughly  consistent  with  health,  but  also  that 
there  may  be  no  perception  of  impurity  by  the  senses,  the 
air  of  the  room  remaining  apparently  as  fresh  and  pure  as 
that  out-of-doors.  To  this  end  de  Chaumont  made  a  large 
number  of  observations  (over  450),  and  found  that  as  long 
as  the  carbon  dioxide  due  solely  to  respiratory  impurity 
did  not  exceed  0.02  per  cent.,  the  in-door  air  did  not  differ 
sensibly  from  that  without,  but  that  when  the  respiratory 
CO2  reached  0.04  per  cent,  the  air  was  rather  "  close " 
and  the  organic  matter  was  becoming  perceptible  to  the 
sense  of  smell.  Subsequent  investigations  have  shown 
that  as  long  as  the  respiratory-  CO2  does  not  exceed  0.02 
per  cent,  it  and  the  concomitant  "  crowd  poison  "  have  no 
perceptible  effect  upon  liealth  ;  consequently,  M'e  may  take 
this  amount  of  carbon  dioxide,  over  and  above  the  amount 
normally  present  at  the  time  in  the  outer  atmosphere,  as 
the  index  of  the  limit  of  permissible  respiratory  impurity 
in  ordinary  inhabited  apartments. 

Having  now  the  two  factors  of  our  problem,  and  pro\i(Ied 
there  are  no  other  sources  of  contamination,  it  becomes 
a  simple  matter  of  proportion  to  determine  the  quantity  of 
fresh  air  to  be  supplied  to  each  individual.  The  equiva- 
lent of  0.02  per  cent,  is  0.0002  cubic  foot  of  carbon  dioxide 
in  each  cubic  foot  of  air,  or  1  ])art  in  5,000.  Tn  a  mixed 
assemldv  at   rest  each  person  exhales  0.6   rubic   f  lot  of 


SOLUTIOy  OF  PROBLEMS   OF   VESTILATIOy.      107 

carbon  dioxide  per  hour.  Consequently,  to  dilute  pruperly 
this  respiratory  COg  and  its  coincident  organic  effluvia, 

each  person  will  need        '        or  3000  cubic  feet  of  fresh 

air  per  hour.  If  the  individuals  are  all  adult  males,  or 
if  thev  are  working,  there  must  be  a  corresponding  increase 
in  the  air  supplied,  running  up  to  6000  or  even  9000 
cubic  feet  or  more  per  head  in  certain  laborious  occupations. 
This  is  the  theoretical  amount  of  pure  air  necessary  for 
good  ventilation ;  but  in  practice  we  find  that  we  can  get 
along  with  safety  and  comfort  with  somewhat  less,  because 
some  of  the  bodily  impurities  are  almost  at  once  carried 
away  and  out  of  the  room  by  the  draughts  through  the 
exits,  or  through  the  cracks  and  crevices  in  the  walls  and 
ceiling'  which  act  as  exits,  and  the  incomino;  air  does  not, 
therefore,  have  to  mix  with  and  dilute  that  portion  of  the 
impurities  that  is  so  immediately  removed.  In  other 
words,  if  ten  per  cent,  of  the  vitiation  is  thus  directly 
taken  away,  ten  per  cent,  less  of  pure  air  is  needed  to 
dilute  the  remaining  contaminants  to  the  limit  of  permissi- 
ble impurity ;  but  as  the  quantity  and  the  consequent 
velocity  of  the  incoming  or  of  the  outgoing  air  diminishes, 
less  and  less  of  the  impurities  are  thus  directly  removed, 
and  experience  teaches  that  almost  the  entire  theoretical 
supply  of  fresh  air  is  actually  needed  in  practice  to  secure 
satisfactory  results. 

Provision  must  also  be  made  for  sufficiently  diluting  the 
i  mpurities  from  other  sources  of  vitiation  whenever  they  are 
present.  Although  combustion-products  are  not  usually  so 
dangerous  as  impurities  from  the  human  body  and  although 
they  generally  accumulate  near  the  top  of  the  room  on  ac- 
count of  their  high  temperature,  which  also  facilitates  their 
escape,  we  should  provide  at  least  1800  cubic  ffct  of  air 


108  VENTILATION  AND   HEATING. 

for  each  cubic  foot  of  gas  burned,  and  ten  times  as  much 
for  each  pound  of  oil  consumed. 

In  sick-rooms  and  hospitals  an  exception  must  also  be 
taken  to  the  equation  in  which  0.02  per  cent,  of  carbon 
dioxide  is  taken  as  the  permissible  respiratory  impurity,  for 
it  is  found  that  the  organic  matter  exhaled  from  the  sick 
is  much  more  offensive  than  that  from  the  healthy,  and  is 
noticeable  to  the  senses  when  the  respiratory  CO2  is  less 
than  0.02  per  cent.  So,  at  least  one-fourth  or  more  of 
clean  air  must  be  added  to  the  quantity  necessary  for  the 
healthy,  and  a  good  rule  is  to  give  the  sick  as  much  as 
possible,  provided  it  be  properly  warmed  and  distributed. 

The  use  of  the  following  formula  will  often  be  of  ad- 
vantage in  solving  problems  relating  to  ventilation,  viz. : 

-  =  d,  where  e  represents  the  amount  of  carbonic  acid  ex- 
r 

haled  in  the  given  time,  r  the  respiratory  COj  in  parts  per 
cubic  foot,  and  d  the  delivery  or  volume  of  fresh  air  in 
cul^ic  feet.^  Example  :  What  will  be  the  respiratory  im- 
purity in  the  air  of  a  room  of  3000  cubic  feet  capacity 
which  has  been  occupied  by  three  men  for  two  hours 
supposing  that  there  has  been  an  ingress  of  9000  cubic 
feet  of  fresh  air  in  that  time?     Here  e  =  0. 7X3X2  = 

4.2,    and    d  =  3000  +  9000  =  12,000.     —  =  12,000  : 

r 

4  2 

— ' —  r=  r  =  0.00035  =  0.035  per  cent,  carbon  dioxide. 
1 2,000  ^ 

Before  considering  the  means  by  whicli  a  sufficient  quan- 
tity of  pure  air  may  l)e  supplied  to  buildings  and  apart- 
ments, it  will  b(;  Nvcll   to  note  the  following  restrictions 

'  By  iillowing  e  to  represent  the  total  contamination  per  hour,  and  r 
to  represent  the  limit  or  extent  of  impurity  in  any  given  case,  this 
formula  can  be  used  for  almost  any  other  ventilation  problem,  whatever 
may  be  the  contaminants  or  source  of  impurity. 


SOURCE  AND   CONDUITS   OF  AIR-SUPPLY.       109 

as  to  the  size  and  height  of  the  rooms.  If  a  room  be 
too  small,  the  air  therein  will  have  to  be  changed  often, 
the  velocity  at  the  inlets  will  be  increased,  uncomfortable 
draughts  will  be  created,  and  the  air  will  not  diffuse  itself 
so  thoroughly  throughout  the  room.  Experience  shows 
that  even  when  the  air  is  properly  warmed,  it  cannot  be 
changed  much  oftener  than  three  times  an  hour  without 
discomfort  to  the  occupants  of  the  room,  unless  the  ven- 
tilating apparatus  be  very  perfect  in  its  workings  and, 
therefore,  expensive.  Consequently,  as  we  take  3000 
cubic  feet  of  fresh  air  to  be  the  average  amount  required 
per  person  per  hour,  the  cubic  space  per  individual  should 
be  at  least  1000  cubic  feet,  with  a  corresponding  increase 
where  the  occupants  are  all  adult  males,  are  all  at  work, 
or  are  in  hospitals. 

Again,  it  must  be  remembered  that  the  difficulty  of 
securing  equable  heating  and  ventilation  increases  M'ith 
the  height  of  the  room  above  a  certain  limit,  and  that 
with  the  sick  especially  a  certain  amount  of  floor-space  is 
necessary,  both  i'or  the  separation  of  patients  and  conve- 
nience of  attendance.  Ten  or  twelve  feet  will  usually  be 
found  to  be  the  safe  limit  of  height  for  all  apartments 
intended  for  continuous  rather  than  temporary  occupation, 
and  consequently  there  should  be  a  minimum  allowance 
of  from  85  to  100  or  more  square  feet  of  floor-space 
per  head,  and  even  an  increase  above  this  in  workshops, 
hospitals,  etc.  However,  there  is  no  objection  to  high 
ceilings  if  one  is  not  limited  as  to  floor-space,  pure  air- 
supply,  and  heat ;  and  they  are  even  advisable  in  rooms 
where  many  lights  are  to  be  burned.  Again,  these  re- 
strictions regarding  cubic  and  floor-space  do  not  neces- 
sarily apply  to  such  buildings  as  churches,  theatres,  etc., 
which  are  occupied  for  only  a  comparatively  limited  time, 


110  VENTILATION  AND  HEATING. 

which  can  be  thoroughly  flushed  out  after  use,  and  in 
which  it  is  evidently  impracticable  to  allot  to  each  person 
the  above  floor-area.  Yet  pains  must  be  taken  in  such  as- 
semblies to  keep  the  atmosphere  pure  by  whatever  means 
are  necessary ;  while  for  school-rooms  and  the  like  there 
must  be  extreme  care  that  the  pupils  are  not  over-crowded, 
and  that  they  have  a  full  supply  of  properly  warmed  air. 

Any  correct  system  of  ventilation,  in  addition  to  the 
above  considerations,  must  take  into  account  the  source 
of  the  air  supplied,  the  distribution,  the  heating  or  cool- 
ing of  the  air  when  necessary,  and  its  relative  humidity. 

The  air  supplied  to  any  house  should  be  taken  from 
well  above  the  level  of  the  ground,  where  it  is  free  from 
contamination  and  is  constantly  changing,  and  not  from 
cellars  or  closed  areas,  where  the  atmosphere  is  stagnant 
and  full  of  impurities.  The  conduits  leading  to  the 
heating  or  ventilating  apparatus  should  also  be  so  arranged 
that  they  may  be  frequently  and  readily  cleaned.  It  is 
well  to  have  them  covered  with  gratings  to  prevent  objects 
being  thrust  into  them,  and  in  some  cases  it  may  even  be 
advisable  to  Alter  the  air  through  coarse  cloth  or  fine  wire 
gauze  to  free  it  from  dust  and  other  impurities.  In  the 
mechanical  system  of  ventilation  adopted  in  the  chemical 
laboratory  of  University  College,  Dundee,  the  air  is  filt- 
ered by  being  passed  through  jute  cloth  (light  Hessian) 
stretched  on  frames  seventeen  feet  long  by  four  feet  wide. 
In  this  case  the  presence  of  the  screen  actually  increased 
the  delivery  of  the  air  by  nearly  10  per  cent.,  probably 
by  preventing  eddies.  The  screens  collected  two  and 
one-half  pounds  of  dirt  in  seven  weeks.  They  last  about 
a  year,  and  the  cost  is  about  2d  (four  cents)  a  yard.' 
In   the  clinical  amphitheatre  of  the   Medico-Chirurgical 

'  Stevenson  and  Murphy,  vol.  i.,  p.  51. 


WINDS  AS    VENTILATING  AGENTS.  Ill 

College  and  Hospital  of  Philadelphia  a  double  thickness  of 
fine  wire  gauze  is  used  to  filter  the  air  after  a  preliminary 
spraying  with  water,  the  result  being  entirely  satisfactory. 

The  air  may  be  kept  in  motion  and  efficient  ventilation 
secured  (1)  by  those  forces  more  or  less  continually  acting 
in  nature,  producing  natural  ventilation,  and  (2)  by  these 
in  combination  with  other  forces  set  in  action  by  man, 
giving  artificial  ventilation. 

Natural  Ventilation. — The  three  main  forces  of  nat- 
ural ventilation  are  diffusion,  the  winds,  and  the  motion 
caused  by  the  difference  in  weight  of  volumes  of  air  of  dif- 
ferent temperatures.  Diffusion  is  constantly  taking  place 
between  all  the  gaseous  constituents  and  impurities  of  the 
air,  and  even  effects  a  change  through  brick  and  stone 
walls,  but  alone  is  insufficient  to  keep  the  air  pure,  though 
it  does  much  to  further  this.  Moreover,  as  suspended  mat- 
ters are  solid,  not  gaseous,  they  are  not  changed  or  re- 
moved by  it.  As  the  rate  of  diffusion  is  inversely  as  the 
the  square  roots  of  the  densities  of  the  gases  concerned, 
the  interchange  goes  on  rapidly  when  there  is  much  differ- 
ence of  temperature  between  the  in-door  and  outer  air, 
and  also  at  the  top  of  rooms,  where  the  warm  impurities 
tend  to  accumulate. 

However,  the  action  of  this  force  should  not  be  ignored 
in  our  calculations  as  being  insignificant,  for  it  is  not  only 
continuous,  but  it  also  affects  the  whole  volume  of  the  at- 
mosphere in  maintaining  its  uniformity  of  composition. 
"  Roscoe  found  that  when  he  evolved  carbon  dioxide  in  a 
room  the  amount  had  decreased  one-half  from  that  cause 
(diffusion)  in  ninety  minutes."  ^ 

Winds  are  powerful  agents  for  ventilation,  and  a  slight 
breeze  passing  through  a  room  changes  the  air  therein 
1  Notter  and  Firth,  p.  194. 


112 


VENTILATION  AND  HEATING. 


many  times  in  the  course  of  an  hour,  and  carries  out  by 
its  force  many  of  the  solid  impurities  not  affected  by  dif- 
fusion. Wind  will  pass  through  walls  of  wood,  brick,  or 
stone,  although  its  progress  is  markedly  arrested  by  much 
moisture  in  the  walls  and  by  paper  or  plaster.  The  aver- 
age rate  of  movement  of  the  wind  is  considerable,  but 

Fig.  15. 


Cowl  or  ventilator  for  aspiration. 


the  disadvantages  in  utilizing  it  in  ventilation  are  the 
uncertainty  of  its  direction  and  velocity,  the  difRciilty  of 
regulating  it,  and  the;  fact  that  it  may  fail  us  at  a  time 
when  we  most  need  its  action.  Tn  winter  it  usually  has 
to  be  excluded  directly  from  our  houses,  because  a  velocity 


WINDS  AS   VENTILATING  AGENTS.  113 

of  five  or  six  feet  per  second  is  not  comfortable  unless  the 
air  be  previously  warmed.  We  may,  however,  take  ad- 
vantage of  the  fact  that  a  small  current  with  a  high  veloc- 
ity will  set  in  motion  a  large  volume  of  air,  and  that  wind 
blowing  across  the  top  of  a  tube  will  cause  an  upward 
movement  of  air  in  the  tube.  This  is  one  reason  why 
there  is  almost  always  a  draught  up  an  unused  chimney 
and  why  it  acts  as  a  good  ventilating  outlet. 

To  utilize  these  perflating  and  aspirating  powers  of  the 
wind,  and  to  prevent  back-draughts  down  chimneys  and 
ventilating  pipes,  we  make  use  of  so-called  ventilators  or 
cowls,  either  movable  or  fixed.  We  can  so  arrange  these 
that  the  force  of  the  wind  either  drives  air  into  the  house 
(perflation)  or  draws  air  out  of  it  (aspiration).  Very 
good  systems  employing  these  have  been  put  in  operation, 
the  air  being  warmed,  if  necessary,  by  passing  it  over 
stoves,  steam  coils,  etc.,  and  they  are  especially  useful 
where  the  inner  air  is  colder  than  that  externally,  and 
where  artificial  methods  of  ventilation  dependent  upon 
heat  cannot  be  employed,  as  in  the  holds  of  ships,  deep 
basements,  etc. 

The  most  important  agent  in  natural  ventilation  is, 
however,  the  movement  produced  by  variations  in  the 
specific  gravity  of  air.  Though  the  wind  might  be  in- 
cluded under  this  head,  being  produced  by  the  same  force, 
the  air  is  moved  independently  of  the  wind,  especially  in 
closed  buildings.  As  the  air  expands  when  heated,  it 
becomes  lighter,  volume  for  volume,  and  rises  because  the 
colder,  heavier  air  pushes  in  beneath  to  occupy  the  space. 
Now  in  all  inhabited  apartments  a  warming  of  the  atmos- 
phere is  continually  taking  place,  not  only  by  the  lights 
and  heating  apparatus,  but  also  by  the  bodies  of  the  occu- 


114  VENTILATION  AND  HEATING. 

pants.  The  consequent  movement  is,  therefore,  a  con- 
tinual though  not  necessarily  an  equable  one,  varying  as  it 
does  with  tiie  temperature  of  the  out-door  air  and  the 
number  and  intensity  of  the  heating  agents  within.  There 
being  such  a  warming  and  movement  of  the  air,  it  follows 
that,  unless  a  room  be  perfectly  air-tight,  some  of  the 
apertures  will  act  as  inlets  and  others  as  outlets,  and  the 
quantity  flowing  out  of  the  room  will  be  practically  equiv- 
alent to  that  flowing  into  it.  Therefore,  though  this  force 
may  not  be  so  powerful  or  efficient  as  strong  winds  at 
certain  times,  yet  being  more  constant,  more  readily 
determined  or  calculated,  and  more  controllable,  it  is 
the  one  most  to  be  considered  in  arranging  a  system  of 
ventilation. 

To  determine  the  velocity  of  the  influx  or  outgo  of  air, 
we  make  use  of  the  law  that  a  fluid  passes  through  an 
opening  in  a  partition  between  two  volumes  of  the  fluid 
with  the  velocity  which  a  body  would  acquire  in  falling 
from  a  height  equal  to  the  difference  in  level  of  the 
fluid  on  the  two  sides  of  the  partition.  In  the  case  of  a 
current  of  air  we  substitute  for  the  difference  of  level  the 
difference  in  pressure  on  the  two  sides  of  the  partition  or 
opening,  and  this  is  expressed  by  the  difference  in  tem- 
perature multiplied  by  the  difference  in  height  of  the 
openings  of  entrance  and  exit,  and  divided  by  491,  -^^ 
representing  the  expansion  of  the  atmosphere  in  volume 
and  the  lessening  of  density  for  each  degree  (Fahrenheit) 
of  rise  in  temperature.     The  velocity  will,  therefore,  equal 


V 


(diff.  in  temp.)  X  (diff.  in  height). 


Example :  What  is  the  velocity  of  the  current  in  a  chim- 
ney 40  feet  high,  the  out-door  temperature  being  20°  F. 


VELOCITY  OF  THE  A  IB-CURRENTS. 
and  in-doors  70°  F.?     Answer  :  V  =  8  ^  P  X  40 


4 


491 


115 


=  8X 


2  +,  or  about  16  feet  per  second. 

In  actual  practice  use  is  made  of  a  table  derived  from 
this  formula,  or  else  the  velocity  is  determined  directly 
by  means  of  the  anemometer.  Allowance  must  be  made 
for  the  friction  of  the  air  against  the  sides  of  the  ducts 

Fig.  16. 


Anemometer,  used  for  measuring  the  velocity  of  air-currents  directly ;  A,  slide 
for  releasing  or  stopping  the  dial  hands ;  E,  support  for  attaching  the  instru- 
ment to  a  staff  or  cane. 

and  against  itself,  amounting  to  from  one-fourth  to  one- 
lialf  of  the  theoretical  delivery,  according  to  the  length, 
size,  straightness,  etc.,  of  the  inlets  and  outlets.  The 
friction  will  be  inversely  as  the  diameter  of  the  openings 
and  directly  as  the  length  of  the  tubes  ;  the  shape  of  the 
openings  also  aifects  it,  and  right  angles  diminish  the 
current  one-half  Accumulations  of  dust  and  dirt  greatly 
lessen  the  velocity. 

The  average  velocity  multiplied  by  the  total  area  of  the 
inlets  or  outlets,  with  a  proper  allowance  for  friction,  will 


116  VEyTILATION  AND  HEATING. 

give  the  quantity  of  air  passing  through  the  rooms  or 
series  of  rooms  in  any  given  time. 

One  of  the  most  dilficult  problems  in  natural  ventilation 
is  to  secure  a  uniform  distribution  of  pure  air  through  the 
rooms,  and  to  remove  the  impure  air  as  fast  as  the  pure 
air  is  supplied,  thus  preventing  its  mixing  with  the  latter. 
Certain  circumstances  always  make  the  question  compli- 
cated :  the  size  and  number  of  inlets  and  outlets,  the  rate 
and  direction  of  motion,  and  the  forces  acting  to  produce 
the  movement  must  always  be  subject  to  constant  change, 
and  must  thus  constantly  alter  the  result.  In  fact,  it  is 
practically  impossible  to  devise  a  plan  that  will  satisfy  all 
conditions  at  all  times,  and  the  best  that  can  be  done  will 
be  to  select  that  one  which  will  give  the  greatest  effi- 
ciency and  most  satisfactory  results  under  all  ordinary 
circumstances. 

The  force  of  diffusion  will  always  act  as  long  as  there 
is  any  difference  of  temperature  and  any  communication 
between  the  exterior  and  interior,  and  no  special  attention 
need  be  given  to  it.  For  reasons  already  given,  we  cannot 
use  the  wind  continually,  but  we  should  employ  it  when- 
ever possible  by  opening  doors  and  windows,  on  account 
of  its  groat  power  for  sweeping  out  solid  impurities  and 
"  crowd  poison  "  and  thoroughly  changing  the  air.  In  cold 
weather,  currents  from  windows,  etc.,  should  be  directed 
toward  the  ceiling,  so  that  they  may  be  diffused  and  par- 
tially warmed  before  reaching  the  inmates  of  the  room. 
Numerous  devices  have  been  suggested  for  introducing  un- 
warmed  out-door  air  without  discomfort,  or  for  diffusing  it 
through  the  room  :  among  these  may  be  mentioned  perfor- 
ated bricks,  or doul)le-paned  windows,  valves,  screws,  etc.  A 
cheap  and  satisfactory  temporary  arrangement  is  to  place  a 
board  about  four  inches  wide  and  as  long  as  the  width  of  the 


DISTRIBUTION   OF  I^X'OMING  AIR. 


117 


lower  window-sash  beneath  the  latter.  Or,  better,  have  a 
light  frame  covered  with  fine  netting  or  wire-gauze,  four 
or  five  inches  wide,  made  to  fit  above  the  upper  sash  :  the 
fresh  air  froai  without  can  now  enter  freely  between  the 
upper  and  lower  sash,  being  reflected  upward  by  the  inner 
surface  of  the  glass  in  the  upper  sash,  and  thus  mixing 
with  warm  air  before  reaching  the  occupants  of  the  room  ; 

Fig.  17. 


Direction  of  air-currents  in  room  lighted  by  gas  and  heated  by  open  grate. 


while  the  frame  at  the  top  of  the  window  becomes  an 
outlet  for  the  foul  air,  the  interference  of  the  netting  or 
gauze  preventing  too  rapid  an  outgo  and  consequent  loss 
of  lieat.  But  in  a  climate  such  as  our  own,  and  in  all 
cold  countries,  special  measures  must  be  taken  during  a 
large  part  of  the  year  for  warming  the  out-door  air  before 
introducing  it  into  occupied  rooms. 


118  VENTILATION   AND  HEATING. 

AVhere  we  intend  to  depend  most  npon  the  third  force 
of  natural  ventilation,  viz.,  the  movement  of  unequal 
weights  of  air,  we  must  provide  other  openings  for  the 
entrance  and  exit  of  the  air  than  the  windows  and  doors, 
so  that  there  will  be  a  practically  constant  movement 
through  the  rooms  in  a  given  direction,  that  we  may  be 
sure  the  air  is  from  a  pure  source,  and  that  we  may  get 
the  utmost  service  from  our  appliances. 

There  is  considerable  diiference  of  opinion  as  to  the  best 
locations  for  inlets  and  outlets,  and  as  the  conditions  are 
necessarily  different  in  every  case  and  so  many  factors 
are  to  be  considered,  it  is  diflBcult  to  lay  down  general 
rules.  It  should  be  an  aim,  however,  to  have  the  air 
well  distributed  throughout  the  room  or  rooms  and  to 
have  no  direct  draughts  from  the  inlets  either  upon  the 
occupants  or  to  the  outlets.  It  is  the  writer's  opinion 
that  usually  the  outlets  should  be  located  near  the  top 
of  the  room,  owning  to  the  tendency  of  the  used  air  to  rise, 
and  because  in  unventilated  rooms  the  foulest  air  for 
some  time  after  its  contamination  will  be  found  nearest 
the  ceiling.  The  products  of  combustion  from  lights, 
etc.,  will  also  practically  all  be  in  the  upper  strata  of  air. 
(Fig.  17.)  If,  however,  provision  is  or  can  be  made  for 
a  constant  and  sufficiently  strong  asjiirating  force  in  the 
outlet  ducts,  it  may  l)e  advisable  to  withdraw  the  used 
air  from  near  the  floor  level  and  below  the  inlet  openings, 
though  not  in  too  close  proximity  to  them,  since  in  this 
way  a  more  thorough  distribution  of  the  incoming  air 
and  a  greater  dispersion  of  its  contained  heat  are  secured. 
This  is  aptly  sliown  in  the  ilhistration  depicting  the  cur- 
rents in  a  room  heated  by  a  ventilating  grate.  (Fig.  18.) 
Tliis  princijde  is  also  involved  in  the  well-known  Smead 
system  of   ventilation    and   heating,  which    still   further 


LOCATION  OF  INLETS  AND    OUTLETS.  119 

Fig.  18. 


Direction  of  air-currents  in  room  heated  by  a  ventilating  grate. 
Fig.  19. 


Illustrating  the  Smead  system  of  ventilation. 


serves  economy  by  carrying  tlie  foul  air  beneath  the  floor 
of  the  room   from  which  it  is  taken,  thus  warming  the 


120  VENTILATION  AND  HEATING. 

floor  with  wliat  heat  the  waste  air  yet  contains  and  secur- 
ing the  utmost  lienefit  and  service  from  the  fuel.    (Fig.  19.) 

The  location  of  the  inlets  should  depend  on  the  tem- 
perature of  the  incoming  air ;  if  it  is  cold,  it  should  be 
admitted  near  the  ceiling,  so  that  it  may  diffuse  and  be 
partially  warmed  before  reaching  the  inmates  of  the 
room  ;  if  it  is  warmed,  it  may  come  in  near  the  floor  or 
below  the  middle  level  of  the  room. 

Where  much  fresh  air  is  required,  it  is  better  to  have  a 
number  of  inlets  and  outlets  than  one  large  one  of  each, 
as  the  distribution  is  then  more  certain.  The  total  area 
of  the  outlets  may  be  the  same  as  that  of  the  inlets,  as  the 
expansion  of  the  air  is  scarcely  sufficiently  great  to  require 
a  difference.  The  outlets  should  all  be  on  the  same  level ; 
otherwise  the  highest  one  will  be  the  one  of  greatest  dis- 
charge, and  often  the  only  one,  the  others  possibly  acting 
as  inlets  and  drawing  air  from  an  impure  source.  As  the 
temperature  varies  from  time  to  time,  and  with  it  the  cur- 
rent, some  arrangement  is  needed  for  regulating  the  size 
of  the  openings  of  the  inlets  or  outlets  to  suit  the  varying 
conditions.  To  supply  3000  cubic  feet  of  air  per  head  per 
hour  a  velocity  of  5  feet  per  .second  will  require  an  inlet 
opening  of  24  square  inches  for  each  person  ;  but  practi- 
cally it  is  better  to  have  a  larger  opening,  as  the  above 
velocity  is  uncomfortable  unless  the  air  be  well  warmed. 
Outlet  tul)cs  should  always  be  protected  from  cold  and 
kept  as  warm  as  possible. 

As  long  as  there  is  a  fire  in  a  grate  or  stove  connected 
with  a  chimney  there  will  be  a  constant  upward  current 
in  the  latter  ;  and  the  area  of  the  chimney's  cross-section 
being  known,  and  the  velocity  determined  by  the  ane- 
mometer or  by  calculation,  as  already  indicated,  the 
amount  of  air  passing  out  of  the   room  in  this  way  may 


'   NUMBER  AND  SIZE   OF  INLETS  AJSD    OUTLETS.    121 

readily  be  determined.  In  this  connection  it  may  be 
stated  that  a  chimney  may  thus  act  as  the  only  outlet  and 
all  other  openings  into  the  room  may  serve  as  inlets, 
especially  when  the  fire  is  brisk,  the  outgoing  current,  of 
course,  being  practically  equivalent  to  the  amount  of  in- 
coming air.  Moreover,  the  outgoing  current  may  be  so 
strong  as  to  overtax  the  capacity  of  the  inlets,  in  which 
case  more  or  less  of  a  vacuum  will  be  created  within,  so 
that  the  outside  pressure  may  cause  down  draughts  in  the 
chimney  from  time  to  time  and  a  driving  back  of  the 
smoke  and  gases  from  the  fire  into  the  room.  The  obvious 
remedy  is  to  enlarge  the  inlet  area  by  opening  a  door  or 
window,  or  to  lessen  the  exit  draught  by  means  of  a 
damper  in  the  chimney.  On  the  other  hand,  the  inlets 
may  be -so  large  and  the  current  so  strong  that  the  air 
coming  into  the  room  cannot  be  properly  warmed,  in 
which  case,  again,  the  size  of  the  outlet  should  be  les- 
sened by  a  damper,  or  there  should  be  an  increase  in  the 
efficiency  of  the  heating  apparatus. 

When  w^e  wish  to  draw  air  from  distant  and  non-com- 
municating rooms,  the  ducts  may  be  led  into  a  chimney 
below  or  just  above  a  fire,  or,  better,  into  a  flue  or  shaft 
alongside  or  encircling  the  heated  chimney.  When  the 
exit  ducts  open  into  a  chimney  or  smoke-stack  the  draught 
is  greater  just  above  a  fire  than  below  it,  but  the  conduits 
should  not  enter  near  the  top  of  the  chimney,  for  there 
the  extracting  power  is  not  so  great  and  there  is  danger 
of  high  winds  blowing  smoke  and  foul  air  back  into  tlie 
rooms.  Outlet  flues  may  be  constructed  alongside  chim- 
neys that  are  being  constantly  used  ;  they  should  be  as 
smooth  as  possible  interiorly,  and  should  be  as  higli  as  the 
adjoining  chimney,  to  avoid  down  draughts.  The  open- 
ings from  the  rooms  into   these  ducts  should  be  as  near 


122  VL'yTILATIuy  A  XL   HEATIXG. 

the  ceiling  as  possible,  to  get  the  benefit  of  the  higher  tem- 
perature of  the  upper  strata  of  air,  unless,  as  previously 
indicated,  there  is  certainty  of  the  extracting  force  being 
constant  and  sufficiently  strong,  when  the  air  may  be 
taken  from  a  lower  level. 

Artificial  ventilation  is  that  which  is  brought  aljout 
by  the  intentional  application  of  the  alx)ve  mentioned  and 
other  forces,  and  by  means  of  special  mechanical  apparatus 
and  devices,  in  contradistinction  to  natural  ventilation, 
which  mav  act  independently  <:>£  human  cognizance  and 
intention.  It  consists  in  either  extracting  air  from  or 
fitrcing:  air  into  a  room  or  buildincr.  or  in  both  tocfether. 
The  object  may  be  attained  by  heating  the  air  by  special 
heating  apparatus  in  the  outlet,  or  by  warming  the  outlet 
itself,  or  by  the  use  of  a  fan,  a  screw,  or  a  steam-  or 
water-jet  in  either  the  inlet  or  outlet. 

In  hospitals  and  other  places  where  a  constant  and  inde- 
pendent supply  of  heat  can  be  afforded,  extraction  shafts 
apart  from  cliimneys  may  be  used.  These  extraction 
shafts  may  be  heate<l  by  fires,  steam  pipes,  or  steam-jets 
at  the  bottom,  or  by  steam  or  hot-water  pipes  coiled 
around  the  sides.  S<3me  system  like  the  following  is  some- 
times used  in  mines  where  large  quantities  of  air  mii~t  lie 
extracted.  There  are  an  entrance  and  an  extraction 
shaft ;  large  fires  are  constantly  maintained  at  the  lx)ttom 
of  the  latter,  the  air  is  drawn  down  the  former,  diverted 
through  all  parts  of  the  mine  by  partitions,  and  finally 
heated  and  carried  up  the  extraction  shaft. 

We  may  also  use  a  jet  of  steam  or  water  in  place  of 
heat  to  extract  air  through  a  shaft,  the  openings  of  the  foul- 
air  ducts  being  just  Ix'hind  the  jet.  It  is  said  that  a  steam- 
jet  may  thus  set  in  motion  over  two  hundred  times  its  own 
bulk  of  air.     Lastly,  fans  driven  by  electricity,  steam-  or 


A  R  TIFICIA  L    YEN  TIL  A  TION. 


123 


water-power  are  employed  to  extract  the  air,  though  these 
are  usually  more  efficient  in  forcing  in  air.  One  of  36 
inches  diameter  at  600  revolutions  per  minute  will  propel 
or  extract  over  18,000  cubic  feet  of  air  per  minute. 

In  ventilation  by  propulsion  or  driving  in  air,  these 
large  revolving  fans  are  generally  used.  Tiie  advantages 
of  this,  the  plenum,  system  of  ventilating  are  the  certainty 

Fig.  20. 


Air  propeller,  with  electric  motor  attached. 

as  to  the  direction  of  current  and  amount  of  air  supplied 
and  the  ease  with  which  the  quantity  can  be  altered  or 
measured,  as  well  as  warmed ;  also,  by  maintaining  a 
slight  excess  of  supply,  leakage  into  the  rooms  of  cold  or 
foul  air  from  without  is  prevented.  The  disadvantages 
are  the  high  cost  of  power  in  most  cases,  the  inconveni- 
ence or  danger  from  prolonged  stoppage  from  accidents  to 


124  VENTILATION  AND  HEATING. 

the  apparatus,  and  some  difficulty  in  distributing  the  air. 
For  instance,  if  it  be  forced  in  through  small  openings  or 
at  too  great  a  velocity,  it  will  not  mix  properly  with  the 
air  of  the  room.  This  last  objection  can  usually  be  ob- 
viated by  giving  special  attention  to  the  size,  direction, 
and  arrangement  of  the  inlet  flues,  and  the  relative  loca- 
tion, size,  etc.,  of  both  the  inlet  and  outlet  openings.  The 
increased  use  of  electric  motors  and  lowered  cost  of  run- 
ning them  will  doubtless  serve  to  make  this  system  of 
ventilation  more  common  in  the  near  future. 

In  very  large  buildings  it  may  be  advisable  or  neces- 
sary to  combine  the  plenum  or  propulsion  with  the  ex- 
haust or  vacuum  system,  using  power  fans  both  to  drive 
in  and  to  force  out  large  volumes  of  air.  In  this  way  an 
almost  ideal  ventilation  may  be  secured,  provided  the 
incoming  air  be  clean  and  be  sufficiently  warmed  by 
means  of  steam  or  hot-water  coils  or  radiators  (see  pages 
140  and  142). 

Parkes  and  Kenwood  summarize  the  essential  and 
practical  points  of  ventilation  as  follows : 

"  1.  When  air  is  heated,  it  expands  and  tends  to  rise ; 
when  air  is  cooled,  it  contracts  and  tends  to  fall. 

"  2.  Cold  air  tends  to  enter  a  room  and  to  move  about 
very  much  as  water  would  ;  and  this  holds  true  so  long  as 
tlie  temperature  of  the  fresh  air  remains  lower  than  that 
in  the  room. 

"  3.  The  extent  of  inlet  provision  is  not  quite  of  the 
same  importance  as  that  for  the  exit  of  foul  air ;  for  if 
foul  air  is  extracted  in  sufficient  quantities,  fresh  air  will 
enter  someho\v  to  replace  it,  as  by  skirtings,  crevices  in 
doors  or  windows,  or  even  through  brick-work  in  walls. 

"4.  While  the  inlet  j)rovision  for  fresh  air  should  aver- 
age 24  square  inches  for  each  individual,  several  small 


PRACTICAL  FOISTS.  125 

inlets  uot  too  near  each  other  are  preferable  to  one  large 
one;  and  the  provision  of  inlet  areas  somewhat  larger 
than  those  of  exit  tends  to  minimize  draughts. 

"  5.  Inlets  should  be  as  low  in  the  room  as  possible — 
/.  e.,  just  above  the  floor  (so  as  not  to  raise  the  dustj — if 
the  outside  air  is  warm  or  has  been  warmed  prior  to 
entry ;  but  at  a  height  of  five  feet  or  more  if  the  outside 
air  is  cold :  otherwise  unpleasant  draughts  are  experienced. 
As  a  further  protection  against  unpleasant  draughts  when 
cold  air  is  admitted,  the  incoming  air  should  be  directed 
upward ;  while  hot  air,  since  it  tends  to  rise,  should  be 
directed  downward. 

"  6.  Outlets  should  be  as  high  as  possible,  and  prefer- 
ably close  to  or  in  the  ceiling ;  and  they  should  have  their 
extractive  powers  maintained  by  means  of  heat  or  of  an 
exhaust  fan,  or  they  are  liable  to  act  as  inlets. 

"  7.  If  possible,  outlets  should  be  so  placed  that  vitiated 
air  is  drawn  toward  them  before  mixing  with  the  general 
air  of  the  room.  


"  8.  The  tendency  for  fresh  air  to  take  a  direct  course 
to  the  outlets  must  be  overcome  by  judicious  selection  of 
the  positions  of  inlets  and  outlets. 

"  9.  Methods  of  ventilation  devised  to  ventilate  croicded 
premises  are  generally  inefficient  unless  the  incoming  air 
can  be  warmed  in  winter  to  about  60°  F. ;  for  efficient 
ventilation  by  cold  air  cannot  be  tolerated,  and  there  is  a 
great  tendency  among  workers  to  close  all  ventilating 
inlets. 

"  10.  With  less  than  250  cubic  feet  of  space  for  each 
person,  ventilation  can  never  be  satisfactory  without  the 
aid  of  mechanical  force. 

"  11.  The  source  of  the  incoming  air  should  be  consid- 
ered.    It  should  nni  ])e  borrowed  from  adjoining  rooms, 


f 


126  VENTILATION  AND   HEATING. 

but  taken  directly  from  the  outside.  One  great  advantage 
of  tlie  more  expensive  mechanical  system  of  ventilation  is 
the  fact  that  sufficient  air  can  ahvay  be  obtained  from  a 
source  that  is  known  and  selected. 

"12.  Ventilation  dependent  on  the  extraction  of  foul 
air  is  more  convenient  and  satisfactory  than  that  in  which 
propulsion  is  mainly  relied  upon  ;  but  the  purity  of  the 
air  is  not  provided  for  so  easily. 

"  13.  AVarmed  air  forced  into  a  room  should  be  raised 
only  to  a  temperature  sufficient  to  prevent  a  feeling  of  cold 
(about  60°  F.).  More  highly  heated  air  is  often  felt  to 
be  over-dry  and  unpleasant." 

House-warming'. — In  cold  countries  there  must  be 
some  resort  to  artificial  heat  in  the  winter  season,  and  as 
this  subject  is  more  or  less  inseparably  and  closely  con- 
nected with  ventilation,  it  may  be  appropriately  consid- 
ered at  this  time.  Cold  is  depressing,  uncomfortable,  and 
sometimes  dangerous  to  the  young  and  aged  and  to  women 
whose  haljits  of  life  keep  them  much  in-doors ;  though 
well-fed,  healthy  adult  men  may  not  be  much  affected 
if  accustomed  to  it.  In  this  country  we  need  a  higher 
temj)erature  in  our  houses  than  in  Great  Britain,  on 
account  of  our  drier  climate;  evaporation  and  conscfiucnt 
C(»oling  of  the  body  take  place  more  rapidly  here,  and  so, 
while  they  are  accustomed  to  a  temperature  of  from  60° 
to  65°  F.,  we  find  from  65°  to  75°  F.  to  be  no  more  than 
comfortal>le. 

It  needs  but  slight  investigation  to  determine  tiiat  we 
practically  make  use  of  but  two  kinds  of  heat — radiant 
and  convected — in  the  warming  of  houses,  and  tli.it  of 
these  the  latter  is  by  far  the  most  generally  eni])loye(l  and 
the  most  economical.  Rddiani  heat,  although  it  is  consid- 
ered t/)  be  the  most  healthful  and  warms  an  object  directly 


HO  USE-  WA EJIISG.  127 

without  raising  the  temperature  of  the  intervening  air,  has 
the  disadvantages  of  utilizing  but  a  small  proportion  of 
the  fuel-value,  of  decreasing  directly  as  the  square  of  the 
distance  of  the  object  from  the  source  of  heat,  and  of  thus 
being  available  only  in  comparatively  small  apartments. 
Our  best  example  of  radiant  heat  is  that  wliich  comes 
from  open  fires,  though  any  highly  heated  object,  as  a 
stove,  gives  off  more  or  less  of  it. 

Heat  that  is  carried  from  one  place  to  another  by  warmed 
masses  of  air,  Avater,  or  steam  is  said  to  be  conveded,  and 
because  of  the  economy  in  its  use  and  the  ease  of  distri- 
bution, especially  in  large  spaces,  it  is  the  kind  most  gen- 
erally used.  Conducted  heat,  which  passes  from  molecule 
to  molecule  of  the  conducting  substance,  acts  too  slowly  to 
be  available  to  any  extent  in  house-heating  and  may, 
therefore,  be  omitted  from  this  discussion. 

Just  here  it  may  be  remarked  that  under  present  con- 
ditions there  are  three  things,  any  two  of  which  we  may 
have  in  cold  climates  or  weather,  but  nijt  all  three  to- 
gether, except  in  rare  instances  :  they  are,  good  ventila- 
tion, efficient  heating,  and  cheapness.  The  reason  for 
this  is  that  any  good  system  of  ventilation  necessarily  and 
continually  carries  off  a  large  quantity  of  air  and  the  heat 
it  contains,  which  latter  is  lost  for  warming  purposes  and 
must  be  replaced  at  the  expense  of  more  fuel.  A  heat- 
unit  cannot  be  used  at  the  same  time  to  produce  ventila- 
tion and  to  warm  oljjects  other  than  the  air  it  keeps  in 
motion.  The  principal  aim,  then,  in  establishing  any  sys- 
tem of  combined  ventilation  and  heating  must  be  to  warm, 
introduce,  and  carry  off  no  more  air  than  is  necessary  for 
the  requirements  of  good  ventilation  and  health,  and  to 
produce  the  heat  for  warming  this  air  and  the  house  itself 
as  economically  as  possible,  though  care  must  also  be  had 


128 


VENTILATION  AND  HEATING. 


to  secure  evenness  of  distribution,  absence  of  uncomfort- 
able draughts,  etc. 

The  usual  appliances  for  house-heating  are  open  grates 
or  fireplaces,  stoves,  and  hot-air,  steam,  and  hot-water 
furnaces.  To  these  may  now  be  added  electrical  heaters, 
but  the  cost  of  maintaining  the  latter  prevents  their  use 
at  present  by  any  but  the  wealthy. 

Fig.  21. 


Jackson's  ventilating  grate.  The  outer  casing  is  cut  away  to  show  space 
and  surface  for  warming  the  incoming  air.  The  air  enters  through  the  oblong 
inlet  (a)  and  passes  to  the  register  opening  (b)  (in  front)  between  and  around 
the  five  smoke-pipes  (f)  above. 

Ordinary  grates  and  open  fireplaces  give  practically 
only  radiant  heat,  and  render  available  only  from  7  to 
1 2  per  cent,  of  the  fuel  efficiency.  They  also  heat  directly 
only  the  surfaces  facing  them  of  objects  in  the  room,  leav- 
ing the  remainder  cold,  and  by  rcasf)n  of  the  strong  current 
u])  the  chimney  are  also  apt  to  bring  in  large  quantities 
of  air  from  witiiout  tliat  has  not  been  properly  warmed, 
and  thus  to  cause  chilling  and  injurious  draughts.  Where 
there  is  some  additional  means  of  heating  the  air  before  it 
enters  the  apartment  and  where  the  chimney  current  is 


STOVES.  129 

controlled  by  a  damper,  they  are  valuable,  not  only  for 
the  good  ventilation  they  produce,  but  for  the  pleasing 
effect  of  the  exposed  fire  as  well. 

To  make  open  grates  more  effective  for  heating,  the 
sides  and  top  should  be  inclined  to  the  back  at  an  angle 
of  135  degrees,  so  as  to  throw  as  many  heat-rays  as  possi- 
ble into  the  room ;  the  fuel  surface  should  be  concentrated, 
and  there  should  be  a  damper  to  prevent  too  rapid  com- 
bustion and  too  much  heat  and  air  escaping  up  the 
chimney.  It  is  to  be  understood,  of  course,  that  the 
objects  warmed  by  the  radiant  heat  of  the  open  fire  do 
in  turn  give  convected  heat  by  warming  the  air  surround- 
ing them. 

If,  however,  the  back  and  sides  of  these  grates  be  sur- 
rounded by  a  space  through  which  air  can  pass  and  be 
warmed  by  the  heat  that  Avould  otherwise  be  wasted,  we 
shall  have  a  much  more  satisfactory  apparatus,  since  we 
thus  get  both  radiant  and  convected  heat  and  may  obtain 
from  25  to  35  per  cent,  of  the  fuel  efficiency.  (Fig.  21.) 
And  if  clean  out-door  air  be  led  into  this  air-space  and  thus 
warmed  before  entering  the  room,  the  ventilation  will  be 
greatly  improved  (see  Fig.  18),  other  inlets  will  be  unnec- 
essary, uncomfortable  draughts  will  be  avoided,  and  there 
will  be  sufficient  heat  provided  for  one  or  more  apartments 
of  moderate  size.  The  air-chamber  at  the  back  should  not 
be  too  small,  and  there  should  be  as  much  heated  surface 
to  warm  the  incoming  air  as  possible. 

Stoves  utilize  a  considerable  percentage  of  the  fuel — 
75  to  80  per  cent,  or  more — but  do  not  remove  much  air; 
so  ventilation  has  to  be  provided  for  in  some  other  way 
and  is  apt  to  be  neglected.  Stoves  may  also  give  off  dan- 
gerous gases  and  products  of  combustion  if  not  properly 
cared  for  or  if  the  damper  in  the  stove-pipe  be  entirely 
9 


130 


VENTILATION'  AND  HEATING. 


closed.  There  should  be  as  much  surface  exposed  as  is 
possible  without  diminishing  the  combustion,  so  that  there 
may  be  increased  radiation  and  that  much  air  may  be 
warmed  moderately  rather  than  a  little  excessively.  It  is 
often  advisable,  especially  in  assembly-  or  school-rooms 
and  the  like,  to  surround  the  stove  with  a  sheet-iron 
cylinder  extending  from  the  floor  toward  the  ceiling,  and 
to  bring  in  between  this  and  the  stove  a  supply  of  fresh 


Fig.  22. 


Jacketed  ventilating  stove.    (Harrington.) 

air  from  witlioiit.  This  air  l)C('onu's  lieatcd,  and,  passing 
out  over  the  top  of  the  cylinder  or  drum,  gives  a  plen- 
tiful supply  of  convected  heat  and  greatly  improves  the 
ventilntion.  (Fig.  22.)  A  suitable  outlet  must,  of  course, 
be  provided. 

Carbon  monoxide  and  other  gases  ar((  known  to  leak 
through  (!ast  iron  when  it  is  highly  heated,  so  that 
stoves  should  not  be  allowed  to  become  too  hot.     The 


GAS  GRATES  AND  STOVES.  131 

production  of  carbon  monoxide  is  most  abundant  soon 
after  fresh  fuel  is  added  to  the  fire,  and  is  evidenced  by 
the  characteristic  bkie  flame  above  the  coals.  If  at 
this  time  the  escape  of  this  gas  into  the  outer  air  is  pre- 
vented by  the  careless  or  accidental  closing  of  a  damper 
in  the  stove-pipe  or  chimney,  it  is  prone  to  pass  through 
the  top  and  sides  of  the  stove  in  the  manner  indicated, 
and  to  cause  the  serious  and  fatal  results  so  often  reported. 
Therefore,  it  should  not  be  possible  to  cut  off  completely 
the  draught  from  any  coal-burning  stove,  nor  should  it  be 
materially  lessened  until  combustion  is  well  under  way. 

Other  objections  to  stoves  that  are  allowed  to  become 
too  hot  are  the  excessive  dryness  of  the  atmosphere  which 
they  cause  and  the  unpleasant  odor  due  to  the  scorching 
of  floating  organic  substances  that  come  in  contact  with 
the  hot  iron. 

The  fuel  most  commonly  used  in  both  grates  and  stoves 
is  either  Avood  or  some  kind  of  coal  (bituminous,  anthra- 
cite, or  cannel) ;  but  gas  may  often  be  advantageously  and 
more  satisfactorily  employed  instead  of  any  of  these,  since 
the  heat  can  be  had  from  it  practically  instantaneously, 
can  be  closely  regulated  in  quantity,  and  can  be  promptly 
checked  when  no  longer  desired,  and  since  there  is  no  pro- 
duction of  dust  or  ashes  in  the  room.  The  main  objection 
to  gas  is  that  for  large  rooms  or  prolonged  or  continuous 
heating,  it  is  usually  more  expensive  than  the  other  fuels ; 
but  this  does  not  hold  good  for  small  rooms,  nor  some- 
times for  isolated  apartments  or  where  warmth  is  needed 
only  temporarily  ;  and  it  is  very  probable  that  before  long 
fuel  gas  will  be — it  can  be  now — supplied  at  rates  which 
will  justify  a  much  more  extended  use  of  such  fuel. 

The  ordinary  kinds  of  gas-grates  and  gas-stoves,  espe- 
cially those  which  consume  the  gas  incompletely,  should  all 


132 


VEXTILATIOX  AXD  HEATING. 


be  constructed  ^vitli  flues  to  carry  off  directly  the  products 
of  combustion,  and  this  particularly  when  any  large  quan- 
tity of  gas  is  used.  Theoretically,  when  the  gas  is  burned 
in  a  properly  adjusted  Bun  sen  or '•' atmospheric"  burner, 
the  ouly  combustion-products  will  be  carbon  dioxide  and 
water,  the  former  of  which  is  rapidly  diffused  into  the 

Fig.  23. 


Section  of  Backus'  portable  steam  radiator  for  use  with  gas. 


outer  air,  as  has  been  shown,  and  is  not  likely  to  be  harm- 
ful in  any  cpiantities  thus  produced,  while  the  aqueous 
vapor  is  beneficial  to  the  atmosjihere  rather  than  otherwise. 
However,  it  seems  that  in  practice  even  these  Bunsen 
burners  may  sometimes  give  to  the  air  a  disagreeable 
odor  (said  to  be  due  to  the  formation  of  acetylene),  and 
so  occasionally  need  flue  connections. 

In  tills  connection  it  may  be  interesting  to  describe  one 


OIL-STOVES.  133 

form  of  gas-heater  which,  so  far  as  the  writer  knows,  is 
unique.  It  is  intended  not  only  to  consume  perfectly  the 
gas  it  uses,  giving  nothing  to  the  air  but  carbon  dioxide 
and  water,  but  also  to  destroy  by  fire  the  impurities  of 
the  atmosphere  of  the  room,  thus  doing  away  with  chim- 
neys or  flues  and  the  necessity  of  much  ventilation.  By 
a  peculiar  arrangement  a  continuous  and  large  current  of 
air  is  made  to  pass  through  the  flame,  thus  burning  the 
impurities  whether  gaseous  or  solid.  The  heat  of  the 
burning  gas  is  also  used  to  convert  a  quantity  of  water 
into  steam,  which,  by  heating  the  containing  chamber 
or  coils  of  pipe  and  these  in  turn  the  atmosphere  sur- 
rounding them,  warms  many  times  the  volume  of  air  pos- 
sible to  heat  by  the  flame  alone.  In  addition,  the  humid- 
ity of  the  atmosphere  is  maintained  by  the  evaporation  of 
water  from  an  open  basin  beneath  the  fire. 

The  ordinary  openings  of  any  room  are  amply  sufficient 
to  allow  diffusion  of  the  excess  of  carbon  dioxide — one- 
half  escaping  in  this  way,  according  to  Roscoe,  within 
ninety  minutes — and  to  permit  the  ingress  of  enough 
air  to  supply  all  the  needs  of  the  inmates  and  of  the  fire 
itself.  Experience  and  careful  experiments  seem  to  show 
that  the  claims  of  the  inventor  are  well  founded,  and  that 
the  aj)paratus  is  healthful  in  its  operation  and  produces 
no  harmful  effects  even  after  continued  use  for  several 
months.  At  any  rate,  there  seems  to  be  no  reason  why 
we  may  not  purify  the  air  by  fire  instead  of  by  dilution 
and  removal,  the  methods  employed  in  the  hitherto  de- 
scribed systems  of  ventilation. 

Oil-stoves  are  now  used  qnite  extensively,  and,  beside 
being  portable,  have  the  same  advantages  as  gas-stoves, 
viz.,  that  a  considerable  quantity  of  heat  may  be  had 
quickly  and  just  as  long  as  it  is  desired,  and  at  a  fairly 


134  VENTILATION  AXD  HEATING. 

moderate  cost.  The  combustion-products  necessarily  mix 
directly  M'ith  the  atmosphere  of  the  room,  and  where 
reasonably  perfect  burning  is  had  doubtless  consist  of 
little  else  than  carbon  dioxide  and  water.  One  pound  of 
oil,  the  hourly  consumption  of  a  rather  large  stove,  will 
require  about  150  cubic  feet  of  air  for  its  complete  com- 
bustion, and  will  produce  about  25  cubic  feet  of  carbon 
dioxide. 

"We  do  not  think  that  the  experience  has  yet  been 
accumulated  which  would  enable  us  to  speak  positively 
of  the  innocuousness  of  a  considerable  admixture  of  car- 
bonic acid  with  the  air  we  breathe;  but  the  knowledge 
that  in  hundreds  of  cases  oil-stoves  are  used  for  heating 
living-rooms  and  even  bed-rooms,  without  apparent  injury 
to  the  occupants,  makes  one  feel  fairly  confident  that  the 
products  of  the  complete  combustion  of  hydrocarbons  are 
not  injurious  when  mixed  with  such  an  amount  of  air  as 
is  sufficient  to  dilute  to  a  proper  degree  the  respiratory 
products.  .  .  .  Experiments  show  that,  provided  the  com- 
bustion of  the  oil  is  complete  and  that  the  ventilation  is 
sufficient  for  the  ordinary  effects  of  respiration,  the  use 
of  oil-stoves  for  heating  purposes  may  be  advantageously 
employed  in  both  day-rooms  and  sleeping-rooms.  The 
efficacy  of  oil-stoves  is  increased  by  placing  over  them 
a  diffiiser  or  radiator,  so  as  to  prevent  the  heated  products 
ascending  direct  to  the  ceiling;  care  needs  also  to  be  taken 
that  only  the  better  kinds  of  mineral  oil  are  used  ;  if 
inferior  qualities  of  oil  are  l)urnt,  perfect  coml)ustion  is 
more  difficult  to  obtain."  ' 

The  ab()V(;  remarks,  as  far  as  tliey  apply  to  the  healthful 
use  of  the  air,  may  probably  be  used  with  equal  justice  in 
regard    to  gas-stoves,   jirovidcd   that   with    such   dilution 

J  Notter  ami  Firth,  p.  228. 


GAS-STOVES. 


135 


their  products  give  no  obviously  harmful  or  disagreeable 
results. 

The  heating  apparatus  thus  far  described  is  such  as  we 
are  accustomed  to  employ  for  warming  the  air  of  single 
oi"  jxjssibly  of  adjoining  rooms.  Where  a  whole  dwell- 
ing or  other  large  building  is  to  be  heated,  it  will  usually 

Fig.  24. 


Spear's  hot-air  furnace. 

be  of  advantage  to  do  this  from  one  point,  and  that  not 
in  any  of  the  living  apartments.  In  this  way  we  shall 
have  a  centralization  of  fuel,  both  unburned  and  burning, 
and  tlie  ability  to  derive  more  heat  from  it ;  a  lessening 
of  the  labor  and  attention  bestowed  on  the  fires;  the  obvi- 
ation  of  much   dust,  dirt,  and   combustion-products   in 


136  VENTILATION  AND  HEATING. 

living-rooms,  and,  presumably,  a  more  equable  and  satis- 
factory warming  of  tiie  whole  building.  From  such  a 
central  point  the  heat  is  distributed  by  hot  air,  hot  water, 
or  steam,  or  by  hot  air  in  combination  with  either  of  the 
other  two. 

Hot-air  furnaces  supply  a  large  amount  of  convected 
but  no  radiant  heat.  There  is  a  very  prevalent  opinion 
that  they  are  not  healthful,  and  that  wherever  possible 
they  should  be  replaced  by  some  other  nieans  of  heating. 
But  when  properly  constructed  and  cared  for,  a  hot-air 
furnace  of  the  proper  size  is  not  only  a  good  heater,  but 
also  a  powerful  ventilating  agent,  for  the  large  supply  of 
air  passing  through  it  into  the  rooms  above  must  in 
turn  find  an  exit  either  through  specially  devised  out- 
lets or  through  the  innumerable  cracks  and  crevices 
around  all  doors  and  windows,  and  the  ventilation  will  be 
accordingly. 

One  frequent  source  of  trouble  is  too  small  a  fire-pot, 
giving  insufficient  heating  surfiice  and  necessitating  too 
rapid  and  too  intense  combustion  of  fuel.  There  should 
be  a  considerable  expanse  of  surface,  never  too  highly 
heated,  so  that  large  volumes  of  air  will  be  moderately 
warmed  rather  than  small  quantities  overheated  and 
"  burned."  Air  too  highly  heated  is  very  dry  and  offen- 
sive to  the  senses;  also,  by  taking  excessive  moisture  from 
the  body  througli  the  skin  and  mucous  membranes  and  by 
exciting  glandular  activity,  it  increases  the  liability  to 
fre(iuent  "colds"  and  congestions.  Moreover,  a  large 
quantity  of  air  moderately  warmed  will  perforce  be  car- 
ried to  all  the  rooms  of  the  house,  warming  them  equably 
and  driving  before  it  the  air  already  there;  whereas  a 
much  smaller  volume,  excessively  heated  by  the  same  or 
even  a  greater  amount  of  fuel,  will  make  its  way  along 


HOT-AIR   FURNACES. 


137 


the  conduits  of  least  resistance  to  a  few  favorably  located 
rooms,  overheating  them  wliile  the  rest  of  the  house  is  un- 
warmed,  and  any  satisfactory  natural  ventilation  is  pre- 
vented. 


Hot-air  furnace,  showing  cold-air  inlet  and  hot-air  flues.    Only  one  of  the 
lateral  branches  of  the  main  inlet  [A)  above  is  shown. 

All  joints  in  the  furnace  must  be  as  nearly  gas-tight  as 
possible  to  prevent  the  combustion-products  passing  from 
the  fire-box  or  smoke-fines  into  the  air-chambers  and 
thence  into  the  rooms  above. 


138  VEXTTLATTOX  AXD  HEATIXQ. 

The  furnace  should  be  located  near  the  cold  side  of  the 
hour^e — that  is,  the  side  on  which  the  prevailing  cold  winds 
impinge — for  it  is  said  to  be  as  difficult  to  drive  the  air 
ten  feet  against  the  wind  as  forty  or  fifty  feet  with  it. 
It  may  also  be  well,  if  the  basement  ceiling  is  low,  to  place 
the  ash-pit  below  the  level  of  the  basement  floor,  in  order 
to  give  sufficient  slope  to  the  air-ducts ;  but  in  every 
case  the  space  beneath  the  furnace  should  be  floored  and 
lined  with  cement  or  asphalt  to  prevent  the  drawing  in  of 
soil-air. 

The  air-supply  should  not  be  taken  from  the  cellar, 
even  though  the  latter  be  apparently  clean  and  free  from 
contamination  with  soil-air,  but  should  come  from  a 
clean  source  out-of-doors,  well  above  the  ground-level 
and  from  the  direction  of  the  prevailing  winds.  The 
cold-air  duct  or  ducts  should  be  screened  at  the  entrance 
to  prevent  the  admission  of  refuse  or  vermin,  should  be 
arranged  to  permit  of  regular  cleaning,  should  have  a 
damper  to  regulate  the  supply  of  air,  and  should  have  a 
cross-section  of  at  least  two-thirds  of  the  combined  sec- 
tional area  of  the  iiot-air  flues  leading  from  the  furnace. 
The  imjiortance  of  a  large  air-inlet  cannot  be  too  strongly 
empluisized,  for  upon  this  feature  may  most  depend  the 
satisfactory  action  of  the  furnace.  It  may  be  desirable  to 
provide  for  filtration  of  the  air  tlirough  coarse  cloth  or 
fine  wire-gauze,  especially  if  there  be  much  dust  in  the 
incoming  air.' 

If  possible,  the  hot-air  fliirs  or  ducts  should  imt  bo  too 
narrow  in  cross-section,  but  round  or  square  to  lessen 
friction  ;  and  for  tlie  same  reason  they  should  be  as  direct 
in  their  course  and  as  nearly  vcilical  as  possible  They 
sliould  l)e  covered  from  the  furnace  to  tiie  register-openings 
1  See  page  107. 


PRACTICAL  POINTS  ABOUT  FURNACES. 


139 


with  asbestos  or  other  non-conducting  material  to  prevent 
the  loss  of  heat  that  otherwise  escapes  from  them  into  the 
cellar  and  between  the  partitions.  Lastly,  their  register- 
openings  into  the  rooms  should  not  face  the  windows  or 
prevailing  winds,  unless  it  be  unavoidable,  for  if  they  do 
the  passage  of  warm  air  into  the  rooms  will  often  be 
almost  if  not  completely  checked. 

The  following  table,  from  Coplin  and  Be  van,  gives  the 
proper  size  for  hot-air  flues  and  registers  : 

First  Floor. 


Size  of  room  in  cubic 

Size  of  pipe. 

Size  of  register. 

feet. 

If  round. 

If  square. 

If  round. 

If  square. 

Less  than  1500 

1500  to  2000    

2000  to  3000 

3000  to  4000 

7  inches 
8 
9 
10 

4X9  inches 
4  X  12      " 
4  X  16      " 

4  X  18      " 

9  inches 
10 
12 
12 

7  X  10  inches 

8  X  10      " 

8  X  12      " 

9  X  14      " 

Economy  will  be  subserved  in  most  cases  by  taking 
care  to  burn  the  fuel  in  hot-air  furnaces  quite  slowly, 
since  in  this  way  larger  quantities  of  air  are  warmed  and 
more  satisfactorily,  and  there  is  also  less  waste  of  heat 
through  the  smoke-flues  and  up  the  chimney.  Moreover, 
it  is  the  experience  of  the  writer  that  by  working  the 
furnace  in  this  way  at  low  pressure,  so  to  speak,  the  air 
from  it  will  be  less  likely  to  become  too  dry,  nor  will  it 
need  the  addition  of  so  much  moisture,  something  essen- 
tially necessary  and  yet  most  often  neglected  where  com- 
j^aratively  little  air  is  excessively  heated. 

The  amount  of  water  to  be  added  also  depends  upon 
the  humidity  and  temperature  of  the  out-door  atmosphere. 


140  VENTILATION  AND  HEATING. 

When  the  latter  is  but  little,  if  at  all,  below  the  freezing- 
point  and  is  almost  saturated,  and  when  the  in-door  air  is 
but  moderately  warmed,  as  suggested,  the  lack  of  added 
moisture  may  scarcely  be  noticed ;  while  if  the  air  without 
be  at  the  same  time  dry  and  yery  cold,  its  actual  content 
of  water  will  be  very  little,  and  much  added  moisture 
will  be  needed  to  make  it  either  comfortable  or  healthful, 
eyen  though  ^varmed  to  only  a  moderate  degree.^ 

"  Concerning'  the  need  of  insuring  a  normal  amount  of 
moisture  in  the  air  of  heated  buildings,  there  is  more  or 
less  difference  of  opinion,  but  the  weight  of  eyidence  from 
a  medical  standpoint,  and  from  our  own  sensations,  points 
to  the  advisability  of  introducing  an  amount  of  moisture 
sufficient  to  bring  the  relative  humidity  of  the  air  to  50 
or  55  per  cent.  .  .  .  Air  at  25°  F.,  saturated  with  moist- 
ure and  then  heated  to  70°,  would  need  over  a  half-pint 
of  water  in  every  thousand  cubic  feet  to  give  it  a  hu- 
midity of  65  per  cent.,  and  this  is  far  in  excess  of  the 
capacity  of  the  ordinary  water-pot  of  the  furnace,  as  is 
seen  when  we  reckon  what  half  a  pint  per  thousand  cubic 
feet  means  in  the  course  of  a  day."  ^ 

Some  recent  tests  by  H.  M.  Smith,  of  Brooklyn,  show 
that  a  relative  humidity  aboye  50  and  a  temperature  of 
about  65°  F.  is  most  healthful  and  comfortable.  "■  With 
a  temperature  of  72  or  74  degrees  and  a  relative  humidity 
of  30  per  cent,  as  compared  with  a  room  at  Ci~i  to  68  de- 
grees and  a  relative  humidity  (jf  about  60  per  cent.,  the 
latter  seemed  the  warmer  and  more  comfortable."     Prof. 

'  Most  modern  furnaces  have  a  water-pan  from  which  evaporation  may 
take  place  freely  into  the  warmed  air,  but  the  filling  of  this,  when  left 
to  servants,  is  so  often  neglected  that  connection  with  the  water-supply 
of  the  house  by  means  of  a  float-valve  or  automatic  cut-oflT  would  better 
serve  to  secure  a  constant  supply. 

•^  Harrington,  pp.  420,  421. 


HUMIDITY   OF   WARMED  AIR. 


141 


Wilson,  of  Milwaukee,  says  further  :  "  About  25  per  cent, 
of  the  cost  of  heating  is  expended  in  raising  the  tem- 
perature from  60  to  70  degrees ;  so  if  we  can  keep  com- 
fortable at  a  temperature  of  65  degrees,  ^ve  shall  have 
saved  at  least  12|  per  cent,  of  the  total  cost  of  heating." 

When  it  is  necessary  to  carry  heat  for  a  considerable 
distance  or  to  warm  larg-e  buildino-s  or  blocks  of  buildiniJ:s 
from  a  central  point,  it  will  be  better  and  more  economical 
to  employ  hot  "water  or  steam  as  the  heat-transmitting 

Fig.  26. 


Humidifier.     The  cotton  M-icking  shown  absorbs  water  from  a  reservoir  below. 
(Hareingtox.) 

agent,  on  account  of  the  high  speciiic  heat  of  the  former 
and  the  great  amount  of  latent  hoat  lield  bv  the  latter.  "  It 
IS  uneconomical  to  convey  heated  air  any  long  distance, 
as^  the  amount  of  lieat  conveyed  per  cubic  foot  of  air 
raised  to  any  practical  temperature  is  so  small  and  so 
easily  lost  in  transit.  On  this  account  IMorin  considers 
the  availability  fof  hot-air  furnaces)  to  be  limited  to  a 
horizontal  range  of  40  or  45  feet  from  the  heating  appa- 
ratus." ^ 

^Stevenson  and  Murphy,  vol.  i.,  p.  117. 


142  VENTILATION  AND  HEATING. 

An  equal  quantity  of  heat,  viz.,  1  thermal  unit,  is  re- 
quired to  raise  1  pound  of  water  or  50  cubic  feet  of  air  1 
degree  F.,  and  accordingly  water  will  carry  more  than  four 
(4.21)  times  as  much  heat  as  an  equal  weight  of  air  at  the 
same  temperature.  "  Further,  a  greater  eifect  is  produced 
when  water,  in  the  form  of  steam,  is  made  the  carrier  of 
heat,  because  1  pound  of  water  vapor  at  100°  C.  (212°  F.) 
will,  in  condensing  to  form  boiling  water,  give  oif  suffi- 
cient heat  to  raise  the  temperature  of  5.36  pounds  of 
water  (or  4.21  X  5.36  =  22.5  pounds  of  air)  from  0°  to 
100°  C.  (32°  to  212°  F.)."i 

Hot-water  heating  may  be  by  either  the  low-pressure 
or  the  high-pressure  system.  In  the  former,  large  pipes 
(generally  4  inches  in  diameter)  are  used,  and,  the  system 
being  open  to  the  air  at  its  highest  point,  the  temperature 
of  the  water  can  never  be  much  above  212°  F.  at  any  part 
of  the  system.  The  water  circulates  comparatively  slowly, 
but,  owing  to  the  large  volume,  conveys  much  heat  from 
the  furnace  to  the  places  where  it  is  needed.  The  high- 
pressure  system  employs  small  but  very  strong  pipes,  the 
water  being  completely  enclosed  from  the  outer  air,  where- 
fore it  attains  a  high  temperature,  usually  about  300°  F., 
and  circulates  rapidly.  The  necessary  expansion  is  pro- 
vided for  by  larger  pipes  partly  filled  with  air  at  the  top 
of  the  circuit.  The  maximum  temperature  is  regulated 
by  the  proportion  of  pipe,  usually  one-tenth,  exposed  to 
the  fire.  Either  of  the  hot-water  systems,  but  especially 
the  low-pr(!Ssurc  one,  requires  careful  planning  and  setting 
to  maintain  evenness  of  circulation  ;  and  when  the  latter 
is  complicat(Hl,  as  by  many  radiators  at  various  levels,  or 
where  a  number  of  circulations  have  to  be  supplied  from 
the  same  boiler,  it  may  be  very  difficult  to  maintain  an 
even  head  and  an  equable  distribution  of  heat  in  all. 
'  Notter  and  Firth,  Treatise  on  Hygiene,  p.  231. 


STEAM  AND  HOT-WATER  HEATING.  143 

"  If  properly  constructed  and  the  heating  planned  for 
when  the  house-plans  are  made,  this  hot-water  system  is 
probably  the  most  economical,  both  in  fuel  used  and 
repairs  demanded."  ^ 

Steam-heating  methods  are  usually  quite  satisfactory, 
not  only  because  of  the  large  cpiantity  of  heat  carried,  but 
also  since  a  rapid  circulation  is  readily  maintained  even 
under  adverse  circumstances.  The  size  of  pipe  used  will 
depend  on  the  extent  of  the  distribution,  but  the  calibre 
of  the  radiator  should  always  be  considerably  larger  than 
that  of  the  supply-pipes  in  order  to  favor  condensation 
and  the  consequent  liberation  of  latent  heat,  and  every 
facility  should  be  provided  for  the  speedy  return  of  the 
condensed  vapor  to  the  boiler.  Care  must  also  be  taken 
to  prevent  the  condensation  occurring  in  such  a  way  as 
to  cause  obstruction  to  the  flow  of  the  steam  and  the  dis- 
agreeable thumping  and  noise  that  result. 

AVith  either  steam-heating  or  hot- water  heating  the 
direct,  the  indirect,  or  the  direct-indirect  method  of 
radiation  may  be  used.  Of  these,  the  direct  method — 
that  is,  where  the  radiators  are  placed  in  the  rooms  to  be 
warmed — is  most  commonly  employed  in  dwellings  and 
other  buildings  of  moderate  size ;  but  it  is  open  to  the 
objections  that  in  itself  it  does  not  bring  about  a  sufficient 
change  of  air,  that  the  necessary  inlets  and  outlets  for  the 
latter  are  rarely  provided,  and  that  when  present  they 
are  independent  of  the  heating  system  of  the  house.  Of 
course,  these  objections  are  wanting  when  the  direct  is 
combined  with  the  indirect  method,  or  when  a  plentiful 
supply  of  pure  air  is  brought  from  without  and  is  warmed 
by  being  made  to  pass  through  the  radiators  (either  open 
or  enclosed  in  boxing)  before  diffusing  through  the  room. 
In  the  indirect  method  the  radiators  are  placed  outside  of 
1  Coj)liii  and  Bevan,  p.  325. 


144  VENTILATION  AND  HEATING. 

the  room  in  suitable  and  convenient  enclosures,  into  which 
fresh  air  is  brought  from  out-of-doors,  and  from  which  the 
warmed  air  is  conveyed  by  suitable  conduits  to  the  re- 
spective rooms  above.  The  dh-ect-indirect  method  locates 
the  radiators  in  the  room,  but  encloses  them  and  provides 
inlets  to  the  boxing  from  without,  so  that  the  entering  air 
must  pass  over  the  heating  surface  and  be  warmed  before 
entering  the  room.  If  properly  arranged,  both  the  indirect 
and  the  direct-indirect  methods  should  furnish  good  and 
ample  ventilation,  the  incoming  warm  air  pushing  the  used 
air  of  the  room  ahead  of  it  through  the  various  openings 
in  the  walls  of  the  room.  Safety-valves  on  steam  boilers 
lessen  the  risk  of  explosions,  and  automatic  thermo- 
regulators  make  it  possible  to  maintain  a  practically 
even  temperature  throughout  the  house  or  building  at 
all  times.  But  there  must  be  some  arrangement  for 
supplying  additional  moisture  to  the  warmed  air,  just  as 
with  hot-air  furnaces,  for,  contrary  to  the  opinion  of 
many,  neither  the  steam  nor  hot-water  systems  increase 
the  atmospheric  humidity. 

In  the  clinical  amphitheatre  of  the  Medico-Chirurgical 
College  of  Philadelphia  the  indirect  system  is  employed, 
the  details  being  as  follows  :  The  out-door  air  is  brought 
from  near  the  roof-level  throuo-li  a  laro-e  shaft  into  tlie 
cold-air  room,  where  it  is  moistened  by  a  spray  and 
whence  it  passes  through  a  dust-filter,  consisting  of  a 
double  layer  of  fine  wire-gauze.  Thence  it  passes  through 
tempering  radiators  (to  raise  the  temperature  partially) 
into  the  revolving  fan,  driven  by  its  own  engine,  whence 
})art  passes  through  a  second  and  larger  radiator  to  be 
further  warmed,  and  jxirt  l)el(»w  tlu;  latter,  the  two  cur- 
rents again  uniting  and,  after  mixing,  ])a.^sing  through  the 
flues  into  the  amphitheatre  above.  In  this  th(j  tenijicra- 
ture  is  regulated  by  a  tlicniiostat,  the  latter  governing  a 


WARMING   OF  A   CLINICAL  AMPHITHEATRE.      145 


damper  (not  shown  in  Fig.  27)  which  always  permits  the 
same  vohime  of  air  to  pass  into  the  flues,  but  controls 
the  respective  proportions  of  heated  and  tempered  air,  so 
tliat  the  mixture  practically  does  not  vary  in  temperature. 
In  this  way  900,000  cubic  feet  of  air  at  a  fixed  tempera- 
ture can  be  supplied  per  hour.     For  the  private  operating- 

FiG.  27. 


steam  radiators  and  blower  used  in  warming  the  clinical  amphithcatru  uf 
the  Medico-Chirurgical  College  of  Philadelphia  by  the  indirect  system.  (The 
casing  of  the  radiators  is  not  yet  applied.)  Tempering  radiator  at  left ;  warm- 
ing radiator  at  right ;  casing  of  fan  between. 

rooms  the  system  is  the  same  except  that  the  tempered 
and  the  heated  air  are  not  mixed,  but  each  is  carried  by 
separate  flues  to  double  registers  in  the  operating-rooms. 
In  this  way  each  operator  can  have  the  temperature  that 
he  desires  in  his  room  at  any  time. 

Another  excellent  method  is  to  use  the  plenum  system, 

10 


146  VENTILATION  AND   HEATING. 

and  to  "warm  or  "temper"  the  incoming  air,  either  before 
or  after  it  passes  through  the  driving  fan,  to  a  tempera- 
ture just  below  that  desired  in  the  rooms,  in  Mhich  steam 
or  hot-water  radiators  are  suitably  located.  The  air  will 
then  pass  from  the  inlets  more  or  less  directly  to  the  radi- 
ators and  be  additionally  warmed  by  them  before  rising 
above  the  lower  levels  of  the  room.  In  this  way  the  cir- 
culation and  distribution  of  the  fresh  air  are  much  im- 
proved, and  there  is  less  likelihood  of  it  going  directly 
from  inlets  to  outlets. 

To  determine  the  amount  of  radiating  surface  needed 
for  any  room,  we  must  multiply  the  volume  of  air  to  be 
heated  per  hour  by  the  difference  between  its  temperature 
in  degrees  Fahrenheit  before  and  after  warming,  and  di- 
vide this  product  by  50,  the  quantity  of  air  in  cubic  feet 
raised  1  degree  F.  by  1  thermal  unit.  This  will  give  the 
number  of  heat-units  required  to  warm  the  air.  Then 
this  quotient  must  be  divided  by  the  difference  between 
the  temperature  of  the  radiating  surfice  and  that  of  the 
air  when  finally  warmed  multiplied  by  1.75,  the  number 
of  thermal  units  given  off  per  hour  by  1  square  foot  of 
hot-water  or  steam-pipe  for  each  Fahrenheit  degree  of 
heat  it  loses.  This  will  give  the  area  of  hot-water  or 
steam-pipe  required  to  warm  the  given  volume  of  air. 
Thus,  to  warm  GOOO  cubic  feet  of  air  per  hour  from   20° 

,     -^o    1-       -ii  •       6000  X  (70  —  20)       .^^^  ,      , 

to    iO     1^.   will    rcquu'e ^ — ■ ^  =  6000  heat- 

50 

units,   and   if  the    surface  of  the    radiator  be   200°    F., 

; =  26.37  square  feet  will  be  the  area 

(200°  — 70°)  X  1.75  ^ 

of  radiating  surface  required.     To  this  must  be  added  at 

least  one-lialf  square  foot  for  each  square  foot  of  window 

glass  ami  for  each  square  yard  of  outer  wall  exposed. 


CHAPTER    V. 

WATER. 

Next  to  air,  water  is  the  most  important  of  all  sub- 
stances necessary  to  human  life.  AVhile  it  has  been  often 
demonstrated  that  man  may  do  without  food  for  a  consid- 
erable length  of  time,  even  for  several  weeks,  he  can  prob- 
ably not  survive  much  more  than  ten  days  without  water. 
Not  only  must  one  have  sufficient  to  supply  the  internal 
wants  of  the  body  and  to  replace  that  lost  by  excretion, 
evaporation,  and  respiration,  but  from  a  sanitary  point  of 
view  a  plentiful  supply  is  also  needed  to  maintain  cleanli- 
ness of  bodies,  clothing,  and  dwellings,  and  oftentimes  to 
remove  sewage,  excreta,  etc.,  froui  the  vicinity  of  inhab- 
ited places.  The  care  of  furnishing  water  in  abundance 
and  of  maintaining  its  purity  is  therefore  entirely  within 
the  domain  of  the  physician  and  the  sanitarian. 

Before  inquiring  into  the  sources  whence  we  obtain  the 
water  that  we  use,  it  will  be  well  to  know  what  amount  is 
required  by  the  body  for  its  daily  needs  and  how  much 
for  other  necessary  purposes,  so  that  we  may  be  able  to 
judge  not  only  whether  a  given  source  furnishes  pure 
water,  but  also  whether  it  gives  a  sufficient  supply  of  it. 

The  average  adult  should  take  froixi  70  to  100  fluid- 
ounces  per  day  for  nutrition  and  internal  needs  of  the 
body  alone — about  one-third  of  tliis  being  a  component 
part  of  the  food  and  the  rest  being  taken  in  as  drink.  The 
writer  is  of  the  opinion  that  the  average  person  does  not 

147 


148  WATER. 

imbibe  enough  water  for  the  most  healthful  action  of  his 
tissues  and  organs.  Certain  it  is  that  in  most  cases  the 
plentiful  use  of  a  good  drinking-water  not  only  greatly 
favors  the  body  metabolism,  but  also  materially  assists  in 
the  flushing  out  and  carrying  away  of  the  various  wastes 
and  excreta  of  the  system. 

In  addition  to  this  we  must  supply  a  sufficiency  for 
cooking  and  for  washing  the  food,  body,  clothing,  Irouse- 
hold  utensils  and  parts  of  the  house  itself,  and  to  remove 
the  household  waste  and  sewage  through  the  drains  and 
sewers  provided  for  that  purpose.  Cleanliness  is  an  essen- 
tial requisite  for  the  preservation  of  health,  and  cleanly 
habits  should  be  inculcated  among  all  classes  of  people 
and  every  facility  provided  for  removing  filth  of  all  kinds 
from  persons,  clothes,  and  dwellings.  This,  of  course, 
cannot  be  done  without  an  abundant  supply  of  water. 

Experience  shows  that  al)out  25  gallons  per  head  per 
day  should  be  furnished  for  the  above  purposes,  and  as 
the  quantity  used  by  domestic  animals,  manufacturing 
establishments,  municipal  needs,  etc.,  must  be  added  to 
this,  50  gallons  or  even  more  per  capita  should  be  the 
daily  quota  wherever  it  is  at  all  possible.  And  though  a 
supply  that  permits  of  excessive  waste  may  be  inadvisable 
and  expensive,  both  in  its  provision  and  on  account  of 
increasing  the  cost  of  carrying  it  away  after  use,  it  is 
always  better  to  have  too  much  than  too  little,  and  the 
disadvantages  of  too  scanty  an  amount  are  much  greater 
than  those  of  one  too  large. 

It  should  bo  stated,  however,  that  most  foreign  cities 
are  supplied  witli  nuicli  k'ss  water  per  capita  than  is 
apparently  needed  by  the  niiiuicipalitics  of  tliis  country, 
and  yet  they  seem  to  have  an  al)undanc('  for  all  necessary 
purposes   and  the   requirements  of  public  health.      For 


AMOUNT  NEEDED  DAILY.  149 

instance,  London,  with  a  population  of  over  five  millions, 
has  an  average  daily  supply  that  but  slightly,  if  at  all, 
exceeds  that  of  Philadelphia  with  one-fourth  the  number 
of  inhabitants ;  while  Berlin,  which  has  about  the  same 
population  as  Philadelphia,  had  in  1893  an  average  daily 
supply  of  filtered  water  of  only  18.4  gallons  per  head,  all 
of  which  was  sold  to  consumers  by  meter,  but  to  which 
must  be  added  considerably  more  that  was  from  wells  and 
other  sources  and  was  exclusively  used  for  manufacturing 
purposes,  running  machinery,  etc.  Undoubtedly  the  quan- 
tity wasted  in  many  of  the  cities  in  this  country  is  exces- 
sive, and  the  cost  of  supplying  that  part  of  the  total  quota 
would  go  a  long  way  toward  improving  and  rendering 
pure  and  safe  the  remaining  part  that  is  absolutely  needed. 
Whether  the  compulsory  use  of  water-meters  is  the  best 
way  of  bringing  about  an  improvement  in  this  respect 
remains  to  be  determined ;  but  it  is  also  a  question  whether 
our  larger  cities,  with  rapidly  increasing  populations,  can 
afford  to  continue  to  expend  the  money  necessary  to  purify 
the  enormous  and  increasing  quantities  of  water  daily 
supplied  to  their  respective  consumers. 

As  onlv  a  small  portion  of  the  quantity  indicated  above 
is  required  for  the  internal  needs  of  the  body,  it  has  been 
suo-ffested  that  two  kinds  of  water  be  furnished  to  each 
dwelling — one  for  drinking  and  cooking  purposes  and  for 
tlie  washing  of  the  body,  to  which  especial  attention  as  to 
jnn-ity  should  be  given ;  and  another  kind  for  all  other 
purposes,  its  composition  and  purity  being  disregarded, 
excepting  possibly  as  concerns  the  hardness.  This  would 
enable  the  authorities  to  furnish  a  water  purer  than  usual 
for  those  needs  wherein  purity  is  of  the  greatest  impor- 
tance, and  would  obviate  the  necessity  of  furnishing  pure 
water  abundantly  for  all  purposes ;  but  the  scheme  would 


150  WATER. 

necessitate  a  double  set  of  reservoirs,  mains,  distributing 
apparatus,  etc.,  thus  materially  increasing  the  cost;  and 
there  would  always  be  present  the  danger  of  the  careless 
or  ignorant  using  the  impure  water  for  bodily  needs,  thus 
increasing:  the  risks  and  bad  results  that  we  wish  to  avoid. 
Therefore,  wherever  there  may  be  an  abundance  of  pure 
water  for  all  personal  and  domestic  purposes,  if  the 
authorities  but  take  pains  to  furnish  it,  it  will  be  best 
to  have  but  one  supply  in  dwellings,  aud  this  as  pure 
and  abundant  as  money  and  the  ablest  sanitary  skill  can 
make  it ;  though  there  may  be  little  or  no  objection  to  using 
a  different  water  for  factories,  stables,  city  functions,  etc. 

As  to  the  question  of  supply  through  meters,  it  may  be 
added  that  the  suggestion  has  been  made  that  the  regular 
charge  for  water  begin  only  after  a  certain  specified  amount 
per  month  per  capita  or  per  household  has  been  furnished 
free  or  at  the  lowest  possible  cost,  thus  doing  away  with 
the  objection  that  those  who  need  the  water  most  for  per- 
sonal and  sanitary  uses  would  be  tempted  to  economize  too 
much  if  thoy  had  to  pay  for  all  they  consumed.  To  com- 
pensate for  this  it  might  be  wise  to  arrange  a  sliding  or 
increasing  price  scale  for  larger  quantities.  Whether  a  city 
could  afford  to  do  this,  Mould  have  to  be  carefully  consid- 
ered, and  would  probably  depend  largely  upon  local 
circumstances. 

Another  method  is  "  to  assess  every  owner  of  premises 
where  water  is  used  (and  measured  by  meter)  a  certain 
moderate,  but  fixed,  snm  yearly,  even  though  water  used 
at  the  regular  rate  per  thousand  gallons  does  not  call  for 
so  much  charge."  This  initial  sum  should  be  consideral)ly 
less  than  the  rate  necessary  luidcr  the  old  method,  and  in 
itself  would  be  an  inducement  to  the  introduction  and  use 
of  meters.     Any  water  used  in  excess  of  the  volume  rep- 


USE   OF   WATER-METERS.  151 

resented  by  this  primary  charge  would,  of  course,  be  paid 
for  at  the  regular  rate. 

Experieuce.  shows  that  meters  greatly  reduce  the  total 
consumption  of  water,  since  it  is  to  the  direct  advantage 
of  each  consumer  to  check  reckless  waste  on  his  own 
premises,  which  duty  is  otherwise  neglected  because  it 
does  not  affect  the  yearly  charge  and  cost  of  water  to  him. 
Meters,  wherever  used,  seem  to  have  materially  reduced 
both  the  cost  of  water  to  the  consumer  and  the  cost  of 
supplying  it  on  the  part  of  the  city  or  other  owners  of  the 
water-works.  It  may,  however,  be  advisable  for  the  latter 
to  own  and  control  the  meters,  as  do  gas-companies. 

Sources. — Practically,  all  drinking-water  has  at  some 
time  or  other  fallen  upon  the  earth  from  the  atmosphere  in 
the  form  of  rain,  hail,  snow,  or  dew ;  but  when  we  speak 
of  its  source  we  have  reference  rather  to  the  immediate 
place  or  locality  from  which  we  collect  it  for  use.  The 
rain  on  reaching  the  earth  is  disposed  of  in  three  ways  : 
part  at  once  evaporates  and  goes  back  to  the  atmosphere, 
part  flows  off  according  to  the  slope  of  the  ground  and 
collects  in  pools  and  streams,  and  part  sinks  into  the 
soil.  The  ratio  which  these  three  portions  bear  to  one 
another  depends  on  the  time,  place,  character  of  soil, 
amount  of  rainfall,  etc.  Consequently,  we  may  classify 
the  sources  of  potable  waters — as  Leffmann  does — as  fol- 
lows :  rain-water,  collected  immediately  as  it  falls  in  the 
form  of  rain,  dew,  snow,  etc. ;  surface-water,  collected  in 
ponds,  lakes,  streams,  etc.,  and  in  free  contact  with  the 
air;  .vihsoil-  or  f/round-ivater,  derived  mainly  from  the  rain- 
or  surface-water  of  the  district,  but  which  percolates  and 
flows  through  the  subsoil  and  is  therefore  not  exposed 
directly  to  the  atmosphere;  deep-ov  artesian-umter,  which 
is  separated  from  the  ground-water  of  the  district  by  one 


1 52  WATER. 

or  more  practically  impermeable  strata,  and  which  accu- 
mulates at  a  considerable  depth  below  the  surface.  Springs 
are  the  result  of  the  out-cropping  of  water-bearing  strata 
below  the  level  of  the  water-line  in  them,  and  furnish 
either  subsoil-  or  artesian-water,  according  to  the  kind 
contained  in  the  respective  strata. 

Maiii-water  is  theoretically  the  purest  at  our  command, 
but  in  reality  it  takes  up  many  impurities  from  the  air  iu 
its  fall,  especially  in  the  neighborhood  of  human  habita- 
tions and  communities,  and  by  the  time  it  reaches  the 
earth  contains  ammonia,  nitrous  and  nitric  acids,  and,  in 
towns,  sulphurous  acid,  soot,  many  bacteria,  and  even 
microscopic  plants.  Moreover,  and  especially  after  con- 
tinued dry  weather,  the  collecting  surface  npon  which  it 
falls  is  apt  to  be  covered  with  dust  and  impurities  of  all 
kinds,  which,  being  taken  up  by  the  rain-water,  tend  to 
make  it  unfit  for  use.  But  if  there  be  some  arrangement 
for  turning  aside  the  first  portion  of  the  rain,  it  contain- 
ing the  most  of  the  impurities,  and  if  the  remainder  be 
filtered  and  stored  in  proper  receptacles,  the  water  may  be 
of  excellent  quality. 

The  main  objection,  however,  to  the  sole  use  of  rain- 
water is  that  dependence  is  placed  upon  a  very  uncertain 
source,  and  one  which  is  especially  apt  to  fail  wlicn  an 
inci-cased  supply  is  most  needed.  The  average  rainfall 
in  Philadelphia  is  about  39  inches  per  year ;  in  very  wet 
years  it  is  about  one-third  more,  and  in  very  dry  years 
about  one-third  less  than  the  annual  average.  Each  inch 
of  rainfidl  gives  4. 07  gallons  per  scpiare  yard  of  area  on 
which  it  falls,  equivalent  to  22,017  gallons  per  acre. 
Allowing  00  square  feet  of  collecting  surface  per  head, 
and  estimating  the  loss  by  evaporation,  etc.,  at  20  per  cent., 
an  annual  rainfall  of  30  inches  would  give  only  about  2 
gallons  per  head  per  day,  or  just  about  sufficient  for  cook- 


SOURCES   OF  DRIXKiyG- WATER. 


153 


ing  and  drinkino-  purposes,  and  none  for  the  other  needs 
of  the  household. 

Rain-water  may  be  collected  fmrn  roofs  or  from  a  plot 
of  o;ronnd  paved  for  tlu'  purpose  with  slate  or  cement,  and 
be  led  bv  proper  conduits  to  a  cistern.  It  should  be  filtered 
(Fig.  28)  before  passing  into  the  cistern,  while  the  cistern 
itself  should  be  such  as  to  give  no  unpleasant  taste  or  in- 
iurious  substance  to  the  water,  should  be  so  situated  that 


Fig.  28. 
Movable  eoverins  stone.  Paying. 


Level  of  ground. 


Catchpir  % 


Cistern 


A  simple  filter  for  rain-water.    (Xottee  and  Firth.)  1 

it  will  receive  no  rubbish  or  impurities  and  that  the  water 

niav  Ije  kept  cool,  and  should  be  cleaned  regularly  and 

sufficiently  often  to  keep  the  water  sweet  and  wholesome. 

As  rain-water  contains  considerable  carbon  dioxide  and 

otiier  gases,  its  .solvent  powers  are  increased,  and  cisterns 

should  not  be  lined  with  lead,  copper,  zinc,  or  iron,  lest 

these  metals  be  taken  up  by  the  water  and  produce  harm- 

1  Fig.  25  illustrates  a  filter  for  an  underground  cistern.  One  of  similar 
construction  can  be  readily  made  for  cisterns  above  ground,  the  latter 
being  always  preferable. 


154  WATER. 

fill  results.  Tiiese  remarks  do  not  apply  to  the  so-called 
rustless  iron  now  much  used ;  but  galvanized  iron  should 
not  be  used,  as  it  may  give  up  zinc  to  the  water.  Cement 
should  also  be  used  in  lining  brick  or  stone  cisterns  instead 
of  mortar,  as  the  latter  may  add  lime  to  the  water  and 
render  it  hard. 

Underground  cisterns  for  storing  rain-water  should  be 
avoided  where  possible,  since  they  are  liable  to  soil-air  or 
sewage  contamination  unless  absolutely  air-  and  water- 
tight. Nor  should  the  overflow  pipe  from  a  cistern  open 
into  a  soil-pipe  or  sewer-pipe  or  drain,  but  always  into 
the  open  air,  since  water  is  very  prone  to  absorb  the  vari- 
ous gases  with  which  it  comes  in  contact  and  the  sewer- 
air  may  readily  contaminate  the  entire  contents  of  the 
cistern. 

Rain-water  is  especially  valuable  for  cooking  and  wash- 
ing on  account  of  its  softness,  water  being  called  "  hard  " 
when  it  contains  an  excess  of  the  salts  of  calcium  or 
magnesium  in  solution.  Hardness  due  to  the  presence 
of  calcium  bicarbonate  is  said  to  be  temporary,  because 
it  disappears  when  the  water  is  boiled,  one  molecule  of 
carbon  dioxide  being  driven  off  by  the  heat  and  leaving  the 
insoluble  calcium  carbonate  beliind.  Hardness  due  to  the 
other  salts  of  calcium  and  magnesium  is  called  ])ermanent, 
because  it  is  not  removed  by  boiling.  In  cooking  with 
water  temporarily  hard  the  chalk  is  precipitated  upon  the 
sides  and  bottom  of  the  vessel,  and,  being  a  non-conductor, 
prevents  tlie  passage  of  heat  and  thus  wastes  fuel. 

Hard  water  may  also  jirevent  the  j^roper  softening  of 
certain  foods,  such  as  ]>eas  and  beans,  in  cooking.  •  In 
washing  and  hinndry  work  the  calcium  and  magnesiinn 
salts  unite  with  the  fatty  acids  of  the  soa])  and  ])revent 
the  formation  of  a  lather  ;  for  instance,  one  grain  of  chalk 
d(.'strovs  tlie  efficiency  of"  about   eight  grains  of  soap.     As 


EA  IN- WATER.  155 

we  do  not  call  a  water  hard  unless  it  contains  more  than 
ten  grains  of  chalk  or  its  equivalent  per  gallon,  and  as 
rain-water  rarely  contains  more  than  one-half  grain  per 
gallon,  it  is  easily  understood  why  the  latter  is  so  valuable 
in  the  kitchen  and  laundry. 

Surface  Waters. — A  water-supply  taken  from  rivers  or 
smaller  streams  not  polluted  by  the  refuse  and  sewage 
from  towns,  factories,  or  cultivated  farm-lands  higher  up 
the  stream,  may  be  fairly  pure  and  safe  to  use.  The  best 
water  of  this  kind  Avill  be  from  hilly  and  uninhabited, 
uncultivated  tracts,  with  many  small  streams  fed  by  con- 
stant springs  and  uniting  to  form  rapid  creeks  and  rivers. 
Such  water  may  be  tinged  slightly  with  vegetable  or 
mineral  matters,  but  in  general  such  coloration  is  harm- 
less. For  storage,  dams  may  be  thrown  across  conveni- 
ent valleys,  thus  impounding  the  water  and  at  the  same 
time  exposing  it  to  the  oxidizing  and  aerating  influence 
of  the  atmosphere  and  allowing  the  solid  impurities  to 
settle  to  the  bottom.  Small  lakes  or  ponds  may  be  util- 
ized to  add  to  supplies  of  this  kind,  provided  they  be  not 
stagnant  nor  have  much  decaying  matter  along  their  banks. 

On  the  other  hand,  water  from  a  stream  which  has 
received  the  sewage  from  a  village  or  town  of  any  size,  or 
the  refuse  of  foctories,  or  the  drainage  from  large  tracts 
of  cultivated  land,  should  be  considered  as  at  least  suspi- 
cious. River-waters  are  generally  hard  and  may  contain 
any  of  the  minerals  in  the  soils  which  they  drain  or  over 
which  they  pass ;  but  the  great  danger  is  from  impurities 
of  animal  origin  poured  into  them  along  their  course. 

It  is  not  safe  to  depend  altogether  on  the  self-purifica- 
tion of  sewage-contaminated  rivers,  as  was  formerly  done, 
though  a  considerable  portion  of  the  sewage  and  filth  un- 
(loul)tedly  is  removed,  })art  l)y  oxidation  by  the  air  in  the 
water,  especially  in  streams  flowing  over  dams,  rapids,  etc.; 


156  WATER. 

part  by  subsidence  or  deposition  along  the  banks ;  part  by 
fish  and  animalculse,  and  much  by  the  myriads  of  sapro- 
phytic bacteria  which  such  waters  contain.  If  no  addi- 
tional pollution  is  added,  what  is  left  unchanged  by  the 
above  purifying  agencies  is  still  further  diluted  by  the 
supplies  of  pure  water  that  every  stream  receives  from 
springs  along  its  banks  and  in  its  bed  and  from  tributary 
streamlets,  so  that,  though  the  water  may  never  be  so  pure 
as  it  was  originally,  it  may  possibly  become  or,  by  proper 
filtration  or  other  treatment,  be  made  a  safe  and  usable 
water.  But  w^iere  the  proportion  of  filth  exceeds  a  certain 
percentage,  and  especially  where  sewage  is  being  constantly 
added,  the  contained  oxygen  is  rapidly  used  up  and  oxida- 
tion ceases,  fish  and  animalculse  cannot  live  in  the  water 
for  lack  of  sufficient  oxygen,  and  though  the  heavier  and 
larger  particles  of  the  sewage  sink  to  the  bottom  or  stick 
to  the  sides,  they  are  stirred  up  and  set  in  motion  by  any 
increase  in  the  velocity  of  the  current.  The  only  remain- 
ino:  agents  active  in  the  destruction  of  the  foul  matter  are 
the  bacteria,  but  in  themselves  they  are  often  insufficient 
for  the  task,  and  the  water  thus  polluted  is  unsafe  for  use.^ 
The  greatest  danger  from  sewage  contamination,  how- 
ever, is  that  it  may  at  any  time  add  to  the  water  the 
germs  of  infectious  disease,  which,  multiplying  rapidly 
and  not  being  surely  removed  or  destroyed  l)y  the  ordinary 
agents  or  methods  of  water-purification,  greatly  increase 

'  Accordinn;  to  the  report  of  the  Rivers  Pollution  Commission  some 
years  af^o,  no  stream  in  England  is  of  suffici(;nt  UMiRth  to  purify  itself 
satisfactorily  of  the  sewage  (contamination  it  is  liable  to  receive.  On  the 
other  hand,  it  is  only  fair  to  state  that,  according  to  a  recent  report 
(April,  ]!)0.'5)  of  the  Commissioner  of  Health  of  (liieago,  very  careful  and 
extensive  investigation  shows  that  the  large  quantity  of  sewage  from 
that  city  discharged  into  the  Illinois  River  has  entirely  disappeared  long 
before  the  latter  emi)ties  into  the  Mississippi  at  a  point  over  250  miles 
from  Chicago. 


SUBSOIL-    OR   GROUND -WATERS.  157 

the  risks  to  health.  It  often  fortunately  happens  that, 
owing-  to  the  hostility  of  the  saprophytic  bacteria  of  the 
^^'ater,  or  to  the  presence  of  certain  chemical  substances,  or 
to  other  unfavorable  conditions,  as  of  temperature  and  the 
like,  these  pathogenic  organisms  do  not  multiply  so  rapidly 
as  they  otherwise  would,  and  are  therefore  not  plentiful 
enough  to  do  much  harm.  But,  as  it  never  can  be  cer- 
tainly told  when  a  water  so  contaminated  becomes  safe  for 
use  again,  and  as  the  population  of  most  towns  and  their 
consequent  sewage  production  are  constantly  increasing, 
while  the  quantity  of  water  in  the  receiving  streams 
remains  about  the  same  or  is  diminishing  from  vear  to 
year,  the  use  of  such  water  should  be  avoided  if  possible, 
or,  if  it  must  be  used,  it  should  be  purified  and  made  rea- 
sonably safe  by  the  most  scientific  and  efficient  means  and 
methods  available. 

AVater  from  large  fresh-water  lakes  will  be  of  the  best 
quality,  provided  it  be  taken  from  a  point  sufficiently 
distant  from  the  shore  to  escape  all  danger  of  sewage 
contamination.  Chicago  apparently  lowered  the  mortality 
percentage  from  typhoid  fever  from  7.2  in  1891  to  an 
average  of  2.1  for  the  decade  1896-1905,  and  to  1.2  for 
1905,  by  preventing  as  far  as  possible  the  discharge  of 
sewage  into  Lake  Michigan  and  by  taking  the  water- 
supply  from  the  lake  at  a  minimum  distance  of  one  mile 
instead  of  1400  feet  from  shore  as  formerly.  Water  from 
small  lakes  or  ponds,  and  even  from  storage  reservoirs,  may 
l)ecome  offensive  to  taste  and  smell  through  the  groAvth  in 
tliem  of  minute  vegetable  organisms,  such  as  the  alga^, 
though  it  is  not  known  that  these  are  prejudicial  to  health. 

Subsoil-  or  Ground-ivatet's. — Ordinarily,  water  loses 
much  organic  matter  as  it  percolates  through  the  soil,  but 
takes  up  considerable  carbon    dioxide  from  the  soil-air, 


158  WATER. 

which  increases  its  solvent  powers  so  that  it  may  also  dis- 
solve some  of  the  mineral  constituents  of  the  soil  through 
■which  it  passes.  When  these  mineral  substances  become 
so  great  in  amount  as  to  give  the  water  a  decided  taste  or 
medicinal  properties,  we  call  it  a  mineral  water;  but 
when  the  inorganic  matter  does  not  render  it  objection- 
able to  the  taste  or  too  hard,  the  water,  whether  subsoil 
or  artesian,  will  usually  be  quite  safe  and  usable  in  so  far 
as  the  mineral  matters  are  concerned. 

Attention  has  already  been  called  to  the  pollution  of 
the  soil.  How,  then,  can  the  water  in  passing  through  it 
lose  its  organic  contents  and  become  pure?  Partly  by- 
mechanical  filtration,  but  mainly  through  the  combined 
action  of  the  saprophytic  soil  bacteria  and  the  oxygen  of 
the  soil-air,  which  rapidly  convert  the  organic  impurities, 
both  suspended  and  dissolved,  into  simpler  and  harmless 
end-j)roducts.  The  substances  of  vegetable  nature  are 
ultimately  resolved  by  these  agencies  into  carbon  dioxide, 
water,  etc.,  while  those  of  animal  origin  and  containing 
nitrogen  give  rise  to  the  various  ammonia  compounds,  or 
may  be  further  oxidized  into  nitrous  and  nitric  acids  and 
their  salts,  all  entirely  harmless  in  the  proportions  in 
wliich  thoy  are  found  in  the  percolating  ground-water, 
but  all  of  great  value  as  nutrients  for -the  higher  plant- 
life  of  the  soil. 

The  rate  of  percolation  has  much  to  do  with  the  com- 
jilcteness  and  perfection  of  this  action,  for  ample  time 
must  be  had  for  the  organic  decompositions  to  occur. 
Therefore,  anything  that  retards  the  downward  flow  of 
water  favors  its  j)urificati<)n,  and  anything  that  increases 
its  movcmeut  decidedly  atl'eets  for  the  Avorse  its  ultimate 
(juality  and  cliaraeter. 

The  importance  of  this  biologic  soil  action  can  scarcely 


PURIFICATION   OF  GROUND-WATER. 


159 


be  overestimated,  and  the  student  should  endeavor  to 
appreciate  not  only  the  bearing  which  it  has  in  the  great 
scheme  of  nature's  adaptation  of  means  to  ends,  but  also 
the  importance  of  our  utilization  of  it  in  the  artificial  puri- 
fication of  our  environment  and  in  the  disposal  of  waste 
matters.  We  must  understand,  however,  that  for  every 
soil  only  a  definite  amount  of  work  can  be  accomplished 
by  the  agencies  mentioned  and  under  the  conditions  exist- 
ing at  any  given  time.  In  other  words,  there  is  here  also 
a  limit  of  permissible  impurity,  and  if  this  limit  is  exceeded, 

Fig.  29. 


Outcropping  of  water-table.    (Harrington.) 


the  conditions  become  imnatural,  the  bacterial  and  chemic 
action  is  inadequate,  and  the  descending  water  is  not 
thoroughly  purified  as  it  percolates  through  the  over- 
charged soil. 

The  subsoil-water  slowly  sinks  through  the  ground  until 
at  some  level  or  other  it  reaches  an  impermeable  stratum, 
where  it  is  retained  in  natural  basins  or  escapes  at  some 
outcropping  of  the  stratum  below  the  water-level,  thus 
forming  a  spring.  (Fig.  29.)  The  level  of  the  water 
in  these   underground    reservoirs  is   constantly  changing 


160 


WATER. 


according  to  the  season,  rainfall,  discharge  from  springs, 
etc.,  though  ordinarily  the  variation  for  any  given  place 
diifers  little  from  year  to  year.  It  is  from  wells  sunk  to 
these  water-bearing  strata  and  from  springs  that  water 
is  obtained  for  the  majority  of  people  who  do  not  live  in 
towns  or  cities  supplied  by  water-works.  These  under- 
ground bodies  of  water  are  in  constant  motion  toward  one 
or  more  outlets  at  more  or  less  distant  points,  but  the  cur- 
rents are  usually  quite  sluggish  owing  to  the  friction  and 
capillary  force  of  the  particles  of  soil  through  which  they 

Fig.  30. 


Representing  the  difference  between  shallow  and  deep  wells,  and  between 
the  high-water  and  low-water  level  ot  the  ground-water:  a,  soil  and  gravel; 
b,  clay  or  rock ;  c,  c,  high-water,  and  d,  d,  low-water  level. 

pass.  For  the  same  reasons  the  surface  of  the  water  is 
not  horizontal  but  curved,  the  curve  l)eing  sharjiest 
near  the  outlet,  and  the  difference  in  level  between  liigh 
and  low  water  is  least  near  the  outlet ;  also,  the  higluT 
the  level  tlie  greater  the  fall  to  the  outlet  and  the  greater 
the  discharge.     (Fig.  30.) 

The  outflow  from  most  continuously  flowing  springs 
represents  the  percolation  through  and  drainage  of  su(!]i 
a  comparatively  large  area  that  it  is  not  probable  that 
any  considerable  proportion  of  this  area  will  be  exces- 
sively  polluted,   nor   that   the   percolate   from    any   and 


WELL- WATER. 


161 


all  over-polluted  parts  of  it  will  be  so  concentrated  and 
charged  with  harmful  impurities  that  the  thoroughly  puri- 
fied water  from  the  remainder  of  the  area  will  not  be  suffi- 
cient to  dilute  it  sufficiently  to  eliminate  all  danger  to 
health  from  its  use.  Consequently,  springs  are  to  be 
ranked  among  the  best  and  safest  sources  of  natural 
waters,  and  general  experience  sustains  the  judgment. 

But  the  remarks  regarding  the  purity  of  spring-water 
do  not  hold  good  for  water  from  ordinary  shallow  wells — 
provided  they  do  not  pass  through  an  impermeable  stratum 
— or  from  springs  where  the  water  passes  almost  directly 


Representing  the  difference  of  percolation  about  cased  (d)  and  uncased 
(e)  wells  :  a,  soil  and  gravel ;  6,  clay  or  rock  ;  c,  cesspool. 


from  surface  to  outlet,  for  in  both  cases  the  filtering  action 
of  the  soil  and  the  removal  of  organic  matter  by  the  pro- 
longed action  of  the  saprophytic  bacteria  are  likely  to  be 
incomplete  and  imperfect.  Likewise,  water  from  springs 
that  drain  a  limited  and  extensively  polluted  area  may  be 
seriously  contaminated,  and  unsafe  to  use. 

Especially  about  Imman  dwellings,  where  wells  are  com- 
monly located  for  the  sake  of  convenience,  are  filth  and 
11 


162  WATER. 

pollution  likely  to  be  carried  into  the  water,  for  sewage 
and  dirt  of  almost  every  kind  accumulate  iu  constantly  in- 
creasing quantity  in  the  soil  about  a  house,  and  always  tend 
to  exceed  the  limit  of  permissible  impurity.  There  is  also 
the  ever-present  danger  of  the  water  receiving  the  specific 
germs  of  disease  from  the  human  wastes  of  the  household, 
no  matter  in  what  condition  the  surrounding  soil  may  be. 

0^ving  to  the  lessening  of  lateral  resistance  the  surface- 
water  passes  rapidly  and  almost  directly  into  the  well 
(unless  the  wall  of  the  latter  be  made  water-tight  to 
almost  the  full  depth),  and  may  carry  with  it  solutions  of 
all  the  impurities  polluting  the  soil  about  the  mouth ;  and 
as  wells  drain  a  very  considerable  area — Parkes  says  one, 
in  ordinary  soils,  whose  radius  is  equal  to  four  times  the 
dej'jth  of  the  well — there  are  few  wells  about  which  such 
an  area  is  not  subject  to  dangerous  pollution.  (Fig.  31.) 
Moreover,  the  influence  of  pumping  or  other  sudden  with- 
drawal of  water  from  the  well  is  even  more  important, 
since  it  extends  a  distance  from  15  to  160  times  the  tem- 
porary depression  of  the  water-level,  and  impurities  may 
thus  be  drawn  into  the  well  which  ordinarily  would  tend 
to  flow  away  from  it.     (Fig.  32.) 

Excepting  the  bacteria,  which  pass  freely  through 
almost  all  soils  when  resistance  to  the  water-current  is 
markedly  diminished,  only  such  portions  of  the  pollution 
as  can  be  dissolved  may  reach  the  water  in  the  well ;  and 
it  is  a  fact  that  many  waters  thus  polluted  are  sparkling 
and  clear,  with  a  pleasant  taste  and  no  bad  odor,  so  that 
any  suspicion  as  to  their  real  character  may  be  want- 
ing. Moreover,  even  though  specific  disease  germs  be 
absent,  there  is  always  danger  that  the  contamination  may 
become  so  concentrated  as  to  produce  serious  results,  and 
this  may  occur  in  various  ways :  («)  the  well  may  be  so 


DEEP   WATERS. 


163 


deep  or  the  character  of  the  soil  such  that  in  ordinary 
weather  the  liquid  passing  through  the  soil  is  so  purified 
that  it  imparts  no  harnifiil  properties  to  the  water;  but  if 
the  soil  is  being  continually  infiltrated  with  dangerous  im- 
purities, and  if  at  length  heavy  rains  or  continued  wet 
weather  supervene,  there  may  be  more  and  more  of  these 
impurities  dissolved  and  carried  into  the  well  until  the 
proportion  of  harmful  matter  in  the  water  passes  the 
safety-line,  and  as  a  result  there  is  marked  illness  or  in- 
creased predisposition  to  disease  among  those  using  the 

Fig.  32. 


Showing  depression  of  water  in  shallow  well  caused  by  pumping:  A,  well; 
B,  cesspool ;  C,  underground  water-curve.    (After  Field  and  Peggs.) 


water ;  or  (h)  in  continued  dry  weather  the  ground-water 
may  be  lessened  to  such  an  extent  that  the  impurities  that 
were  formerly  well  diluted  become  sufficiently  concentrated 
to  cause  sickness,  even  though  there  be  no  unusual  pollu- 
tion of  the  soil  about  the  well ;  or  (c)  the  water-level  in  the 
well  being  suddenly  or  persistently  lowered,  a  greater  area 
is  drained  and  additional  collections  of  sewage  may  flow 
into  the  well.     (Fig.  32.) 

Dcej)  Waters. — Deep  wells  are  those  which  pass  through 
an  impermeable  stratum,  and  so  do  not  get  their  supply 


164 


WATER. 


from  the  subsoil-water.  The  relative  depth  of  two  wells 
is  no  exact  criterion  as  to  their  classification,  as  the  shal- 
lower one  may  really  be  a  "  deep  "  one  and  the  deeper  a 
"  shallow  "  one,  according  to  the  presence  or  absence  of 
the  impermeable  stratum.  Artesian  wells  are  very  deep 
wells,  piercing  one  or  more  impermeable  strata. 

Sometimes  the  water  rises  and  flows  out  of  the  mouth 
of  a  deep  well,  in  which  case  the  supply  is  drawn  from  a 
water-bearing  stratum  between  two  impermeable  ones,  and 

Fig.  33. 


Representing  the  spontaneous  flow  of  deep  or  artesian  wells,  b  and  c: 
a  a,  water-level  in  deep  pervious  strata,  ff;  a,  intermittent  spring  at  out- 
cropping of  F  F  above  impermeable  stratum,  e  e;  d,  shallow  well  in  upper  per- 
vious strata.    (Wilson.) 


wliicli  has  its  only  outcroppings  higher  than  the  top  of  the 
well.  (Fig.  33.)  The  water  accumulates  in  this  natural 
reservoir  above  the  level  of  the  well-mouth,  and  is  forced 
out  wlien  an  opening  is  made  through  tlie  uppermost  im- 
permeable stratum.  Deeji  well-water  is  apt  to  be  of  much 
better  quality  than  that  from  shallow  wells,  since  it  usually 
represents  the  total  percolation  from  a  very  large  extent 
of  ground  surface,  in  comparison  to  Avhich  the  comliined 
areas  and  amount  of  pollution  within  its  limits  are  in- 
significant, the   possible   impurities   in   the  water   being 


DEEP   WELLS.  165 

consequently  reduced  by  dilution  to  much  below  the  dan- 
o;er-point.  It  is  for  the  same  reason  that  there  is  such  a 
difference  in  the  quality  of  spring-water  and  of  tliat  from 
most  shallow  wells.  Though  the  two  waters  seem  to  have 
a  common  source,  one  is  the  composite  water  of  a  large 
district,  of  which  the  average  imparity  or  contamination 
per  unit  of  surface  may  be  infinitesimal  ;  the  other  is 
maiulv  the  special  percolate  from  a  limited  area,  which  is, 
for  the  reasons  given,  particularly  liable  to  be  highly  and 
dangerously  polluted.^ 

Artesian  or  deep  well-water  will  also  likely  be  very  free 
from  organic  matters,  but  possibly  heavily  charged  with 
mineral  salts.  Should  these  latter  not  be  present,  the 
water  will  probably  be  of  excellent  quality  ;  though  if  the 
well  be  very  deep,  it  mav  be  too  warm  for  immediate  use 
as  a  potable  water. 

Frequently  well-water,  and  that  most  iiften  from  shallow 
wells,  is  the  only  kind  available,  especially  in  cramtry  dis- 
tricts. In  such  cases  care  must  be  taken  that  impurities 
are  kept  out  of  the  well  by  all  possible  mean.s.  If  this  be 
done,  water  may  often  be  had  of  excellent  quality.  The 
area  about  all  wells  should  be  kept  clean,  and  the  well 
should  be  as  distant  as  possible  from  anv  source  of 
contamination,  especially  if  the  latter  be  a  constant 
one.  Wells  should  be  walled  or  cased,  shallow  wells 
to  below  the  water-level  and  deep  wells  to  the  first 
impermeable  stratum  if  possible,  in  order  to  cause  the 
water  to  percolate  through  as  much  soil  as  possible  before 
entering  the  well,  in  this  way  checking  the  rapidity  of 

'  Of  course,  the  water  in  shallow  wells,  as  in  others,  is  being  continu- 
ally changed  by  the  onward  movement  of  the  underground  current :  but 
where  this  is  slow  in  comparison  with  the  percolation  from  the  surface, 
the  impurities  of  the  latter  will  be  in  excess  in  the  well-water, 


166  WELLS. 

its  descent  and  prolonging  the  biologic  action  of  the 
top-soil/  Wells  should  also  have  a  properly  constructed 
curb,  to  keep  out  splashings  and  drippings  of  muddy  or 
dirty  water. 

In  this  connection  Sedgwick  says  :  "  Excepting  those 
cases  in  which  cracks  or  fissures  in  the  earth  allow  direct 
coniniunication  between  polluting  sources  and  wells  of 
drinking  water,  the  author  is  strongly  of  the  opinion  that 
in  most  cases  in  which  infection  exists  in  wells,  the  pollut- 
ing material  has  found  its  way  in  from  the  top."  "  When 
one  reflects  on  the  carelessness  with  which  wells  used  as 
sources  of  drinking  water  are  exposed  to  the  access  of  filth 
from  the  top,  such  wells  often  being  only  loosely  covered 
by  planks,  it  is  easy  to  see  that  from  the  boots  of  work- 
men, or  from  children  playing  on  the  planks,  or  from 
poultry  walking  about  and  carrying  infection  on  their 
feet,  pollution  may  take  place."  ^ 

We  must  not  forget  that  wells  drain  a  large  area.  As 
the  srround-water  has  a  constant  movement  in  the  direc- 
tion  of  natural  outlets,  the  well  should  be  so  located  that 
the  current  flows  from  it  toward  any  near-by  cesspool  or 
other  source  of  pollution.  The  direction  of  the  under- 
ground  current  can   generally  be   determined   l)y   noting 

'  As  the  saprophytic  and  nitrifyiiii?  hactcria  aro  07ily  foniul  Jiornially 
in  tho  first  few  feet  of  top-soil,  wliere  the  conditions  are  favorable  to 
their  existence  and  growth,  we  cannot  expect  to  liavo  any  further  action 
hy  them  after  the  water  reaches  its  underground  level  and  begins  to 
move  toward  its  outlets.  Nor  will  there  be  any  filtration  in  this  on- 
ward progress,  for  that  has  been  accomplished  in  the  upper  layers.  It 
is  for  this  reason  that  the  filtrate  from  cesspools  and  similar  pits  is  not 
organically  7)urified,  l)ut  is  especially  obnoxious  and  dangerous  as  it 
traverses  the  soil,  for  the  bottoms  of  such  pits  are  usually  below  the  bio- 
logic level,  and  th(!re  is  also  in  th(^m  a  lack  of  the  oxygen  necessary  to 
maintain  the  action  of  the  nitrifying  bacteria. 

^  Pnitc'iples  of  HaiiUai-y  Science  awl  the  I'lihlic  llcallh,  190:2,  p.  .351. 


DRAINAC4E-AREA   OF  WELLS.  167 

the  location  of  the  nearest  spring  or  water-course,  by 
observing  the  dip  of  the  underlying  strata,  or  by  digging 
lioles  at  equal  distances  about  the  well  and  dissolving  salt 
or  an  aniline  dye  in  them  in  turn,  and  testing  the  water 
from  the  well  after  a  time  for  the  salt  or  color.  If  a 
well  be  much  deeper  than  a  neighboring  cesspool,  it  may 
drain  from  the  latter,  even  in  opposition  to  the  ground- 
water current,  especially  if  the  water  in  the  well  be  sud- 
denly lowered.  Again,  dangerous  imparities  have  been 
carried  into  wells  from  long  distances  through  fissures  or 
crevices  in  rock.  Harrington  cites  the  case  of  a  well  which, 
"bored  500  feet  into  red  sandstone,  drained,  through  fis- 
sures, all  the  shallow  wells  in  the  vicinity.  These  being 
of  no  use  as  wells,  were  then  utilized  as  cesspools,  and 
draining  again  through  the  fissures,  caused  the  well  to 
become  so  foul  that  it  had  to  be  abandoned." 

The  water  from  the  well  should  be  frequently  tested  for 
chlorides  and  nitrates,  these  indicating  sewage  contamina- 
tion, and  this  should  be  done  especially  after  heavy  rains 
and  also  when  the  water  in  the  well  becomes  low.  The 
taste  and  odor  of  the  water  should  also  be  noted  after 
standing  for  a  time  or  on  being  heated.  Some  other 
sources  should  be  sought  whenever  such  tests  show  con- 
tamination or  when  tliere  are  cases  of  infectious  disease 
near  at  hand.  Boiling  the  water  and  filtration  are  always 
to  be  recommended  whenever  there  is  the  least  suspicion 
as  to  impurity  or  infection. 

Shallow  or  subsoil  wells  in  thickly  settled  towns  should 
not  be  used  to  supply  drinking-water  or  cooking- water, 
as  the  soil  is  always  more  or  less  saturated  with  filth  and 
sewage,  and  it  is  practically  impossible  in  such  places  to 
locate  a  well  which  will  not  be  in  constant  danger  of  re- 
ceiving harmful  impurities  from  some  source  or  another. 


]  68  WATEE. 

In  an  investigation'  made  by  the  author  in  1904  he 
discovered  that  the  incidence  of  typhoid  fever  is  appar- 
ently greater  in  districts  essentially  rural,  and  not  in  those 
which  include  the  great  cities,  many  of  which  latter  are 
known  to  have  high  death-rates  from  this  disease,  and  all 
of  which  have  water-supplies  which  may,  if  not  properly 
cared  for,  serve  as  common  carriers  of  infection  to  their 
enormous  populations.  As  the  data  from  which  this 
study  was  made  were  taken  from  the  Report  on  Vital 
Statistics  of  the  U.  S.  Census  of  1900,  it  must  be  remem- 
bered that  all  cities  and  towns  of  less  than  8,000  popula- 
tion are  classified  with,  and  that  they  collectively  make 
up  a  large,  if  not  the  greater,  part  of  the  so-called  rural 
population.  Now,  in  the  smaller  towns  and  villages  it  is 
more  than  probable  that  the  inhabitants  will  be  supplied 
from  private  and  shallow  wells  and  cisterns,  rather  than 
from  common  sources,  such  as  reservoirs,  springs,  arte- 
sian wells,  or  modern  filter  plants,  and,  consequently,  there 
is  continual  danger  in  such  communities  of  the  water 
being  contaminated  by  neighboring  cess-pools  and  other 
sources  of  pollution,  this  danger  rapidly  increasing  as  the 
villages  grow  in  size,  for  these  wells  and  cess-pools  are 
brought  closer  together,  and  the  entire  body  of  ground- 
water supplying  the  wells  is  correspondingly  more  liable 
to  be  polluted  beyond  the  limit  of  safety  or  to  become  at 
any  time  the  common  carrier  of  infection.  Hence  it  is 
easy  to  understand  how  the  so-called  rural  populations 
actually  have,  as  a  rule,  a  relatively  higher  sick-  and 
death-rate  from  typhoid  fever  than  do  the  dwellers  in 
large  cities;  and  it  should  be  equally  evident  tliat  it  will 
be  the  part  of  wisdom  for  small   communities  to  employ 

'    Typhoid  Fever  in  Relation  lo   the    Vrhnn  ami   Rural   Population  of  the 
United  Staten  ;  American  Medicine,  April  22,  190."),  pp.  649-652. 


WATER-SUPPLY  AND   TYPHOID  FEVER.        169 


Fig.  34. 


Showing  death-rates  from  typhoid  fever  in  1894  in  sixty-six  cities,  grouped 
aoeordingto  the  quality  of  their  drinking-water.  {Repri)diiced  witli  the  per- 
mission of  the  author,  Mr.  .James  U.  Fucrtes,  and  of  tlie  Association  of  Civil 
P^ngineers  of  Cornell  University.) 


170  WATER. 

every  possible  means  to  secure  improved  and  non-polluted 
water-supplies  for  the  common  use  of  their  respective 
populations. 

The  decision  as  to  the  quality  of  any  water  must  in  each 
case  be  determined  by  all  the  circumstances  available 
which  relate  to  it,  and  these  should  all  be  thoroughly  in- 
vestigated before  rendering  an  opinion,  as  some  of  them 
may  counteract  the  others.  However,  other  things  being 
equal,  the  value  of  a  water  will  probably  be  in  accord 
with  the  following  table  : 

rl.  Spring-water,  ]  Very- 
Wholesome  <  2.  Deep  well-water,  >      palatable. 
V  3.  Water  from  unpolluted  streams,  |  Moderately 
f  4.  Stored  rain-water,  >      palatable. 


Suspicious 

(  5.  Surface-water  from  cultivated  land, 


>  Palatable. 


Dangerous  I  ^-  Sewage-polluted  river-water,  J 

(  7.  Shallow  well-water,  ' 

A  good  potable  water  should  be  perfectly  clear,  free 
from  odor  or  taste,  cool,  well  aerated  and,  if  possible,  soft 
or  with  only  a  mild  degree  of  hardness.  Circumstances 
must  determine  the  amount  of  dissolved  matters  permis- 
sible; what  is  an  excess  in  one  case  might  not  be  so  in 
another. 

We  may  also  classify  waters  as  follows  :  1.  Pure  and 
wholesome  water.  2.  Usable  water.  3.  Suspicious  water. 
4.  JJangerous  water.  (See  chart  on  page  169  and  table  on 
page  213.)  l*urc  waters  and  usable  waters  may  be  used 
without  nitration  ;  those  of  the  third  class  should  be  fil- 
tered before  (listril)uti()n,  and  also  at  the  house  before  use, 
if  ])o.ssible,  and  a  j)urer  source  souglit  or  all  scwage- 
])ollution  prevented.  Those  of  the  fourth  class  should 
not  be  used  at  all  except  when  absolutely  unavoidable, 
and    then    only    after    purification    by  all    the    means  at 

('(UihikiikI. 


DISEASES  DUE   TO  IMPURE   WATER.  171 

Inasmuch  as  most  large  cities  must  from  necessity  fur- 
nish a  water  of  the  second  or  third,  and  occasionally  even 
of  the  fourth  class,  such  water  should  be  purified  as  much 
as  possible  before  distribution  by  storage  for  a  time  in  set- 
tling reservoirs  and  by  some  effective  system  of  filtration, 
combining  these  with  chemical  treatment  if  necessary. 
As  much  of  the  organic  matter  is  oxidized,  and  many  of 
the  pathogenic  bacteria  are  destroyed  by  saprophytes  and 
other  causes  while  the  water  is  standing  in  the  settling 
reservoirs,  and  as  properly  constructed  and  well-managed 
filters  are  even  more  efficacious  to  this  end,  a  water  origin- 
ally suspicious  or  worse  may  often  be  made  usable  by  the 
above  means  properly  employed.  Not  only  must  the 
storage  reservoirs  and  filtering  apparatus  be  kept  clean 
and  in  good  working  order,  but  care  must  also  be  had 
that  the  distributing  apparatus  does  not  permit  soil-air  or 
sewer-gas  or  sewage  to  be  drawn  in  through  leaks  in  the 
mains  at  times  when  the  flow  is  intermittent,  and  that 
lead  pipes  are  not  used  for  conveying  drinking-water  if 
tlie  character  of  the  water  is  such  that  it  acts  on  that 
metal. 

Diseases  Caused  by  Impure  Drinking-water. — A 
polluted  water  may  carry  the  organisms  of  infectious  dis- 
eases, or  it  may  produce  or  favor  the  development  of  dis- 
eases which  are  not  due  to  specific  germs.  In  addition  to 
these,  and  of  at  least  equal  importance  from  a  sanitary 
l)()int  of  view,  is  the  depressed  state  of  the  system  that 
tlic  habitual  use  of  impure  drinking-water  causes,  and  the 
l)redisposition  to  disease  that  ensues.  By  the  faculty  of 
accommodation  and  through  long  habit  a  community  may 
become  so  protected  against  an  imj)ure  water  as  to  mani- 
fest no  striking  symptoms,  while  strangers  may  be  seri- 
ously aifected  by  it ;  but  even  in  such  a  case  the  condition 


172  WATER. 

of  those  habitually  using  the  water  will  probably  be  more 
or  less  depressed  and  not  that  of  perfect  health. 

The  non-infectious  diseases  likely  to  be  caused  by  im- 
purities in  the  drinking-water  are  primarily  those  aflPecting 
the  alimentary  tract,  as  dyspepsias,  diarrhoeas,  and  other 
disturbances  having  their  origin  in  severe  gastric  or  intes- 
tinal irritation.  So,  also,  impure  water,  even  though  it 
does  not  contain  the  actual  germs,  may  have  much  to  do 
in  bringing  on  an  attack  of  typhoid  fever  or  specific  dys- 
entery by  so  irritating  the  intestine  as  to  make  it  especially 
receptive  to  the  cause  of  the  disease  when  introduced  from 
another  source. 

Large  quantities  of  the  sulphates  of  calcium  and  mag- 
nesium are  thought  to  have  special  influence  in  causing 
dyspepsias,  with  loss  of  appetite,  pain  at  the  epigastrium, 
etc.  An  excess  of  iron  in  water  is  also  prone  to  produce  con- 
stipation, headache,  loss  of  appetite,  and  malaise.  Goitre 
and  the  formation  of  vesical  calculi  are  each  supposed 
to  be  due  to  mineral  or  inorganic  impurities,  though 
the  true  relation  of  impure  drinking-water  to  these  dis- 
eases is  still  unsettled.  "  It  has  long  been  a  popular 
opinion  that  drinking  lime-waters  gives  rise  to  calculi  of 
the  oxalate  and  phosphate  of  calcium,"  and  the  "  opinion 
that  impiuv  water  is  the  cause  of  goitre  is  as  old  as  Hip- 
pocrates and  Aristotle."  Further  study  of  the  principles 
underlying  the  treatment  of  goitre  with  glandular  extracts 
may  make  it  easier  to  determine  ^vlletller  impure  Avater 
has  a  causative  influence  in  the  production  of  this  disease. 

Diarrhfca  may  be  caused -by  any  of  the  following  im- 
purities in  water :  suspended  substances  of  any  kind,  but 
es])ecia]ly  those  of  fecal  origin  ;  dissolved  animal,  vege- 
table, or  mineral  matters,  and  fetid  gases.     The  diarrhoea 


TBAXSMISSION  OF  INFECTION  BY   WATER.     173 

produced  by  any  of  these  contaminants  may  be  so  severe 
as  to  simulate  true  dysentery  and  cause  doubt  as  to  the 
(hagnosis. 

Certain  metals  may  be  taken  up  from  the  earth's  strata, 
or  from  the  lining  of  cisterns,  etc.,  and  may  produce  their 
characteristic  toxic  symptoms  in  the  system.  Lead  is  one 
of  these  metals,  and  it  will  be  well  to  note  here  the  waters 
that  are  especially  apt  to  take  np  this  metal.  Pure  waters 
and  those  containing  much  oxygen  act  powerfully  on  lead, 
as  do  those  containing  organic  nitrates  and  nitrites,  espe- 
cially ammonium  nitrate.  Waters  containing  carbon  di- 
oxide and  the  salts  of  calcium  and  magnesium  and  those 
free  from  absorbed  gases  act  least  on  lead,  and  carbon 
dioxide  seems  even  to  protect  lead  by  forming  an  insolu- 
ble carbonate  on  leaden  surfaces,  but  water  containing  car- 
bon dioxide  may  take  up  lead  for  a  time  from  new  pipes 
until  the  insoluble  carbonate  is  deposited  within  them,  and 
it  has  been  shown  that  in  some  cases  wherein  cold  Avater 
does  not  act  upon  the  metal  hot  water  will  dissolve  a  small 
but  appreciable  quantity  of  it.  Copper,  zinc,  and  arsenic 
are  also  metals  that  may  be  taken  up  by  certain  waters, 
and  that  may  cause  serious  results  from  the  use  of  the 
latter.  Lead  -is  more  easily  dissolved  if  other  metals  are 
in  contact  with  it,  probably  owing  to  electrolytic  action. 
Lead  should  not  be  used  for  pipes  nor  to  line  cisterns 
unless  suitable  tests  show  that  the  water  does  not  affect 
it,  nor  should  any  water  be  used  in  which  the  tests  shoAV 
more  than  one-thirtieth  of  a  grain  of  lead  per  gallon. 

Of  the  infectious  diseases,  germs  of  typhoid  fever, 
cholera,  and  dysentery  are  usually  carried  into  the  system 
by  the  drinking-water,  while  the  same  is  often  true  of 
scarlet  fever,  diphtheria,  and  kindred  diseases,  and  possi- 


174  WATER. 

bly  of  malaria.^  But,  as  with  tlie  impurities  causing  non- 
infectious disturbances,  water  containing  disease  germs 
may  sometimes  be  used  for  a  long  time  by  those  accus- 
tomed to  it  without  the  deveh)pment  of  the  specific  mal- 
ady, and  it  may  only  be  after  the  system  is  weakened  by 
excesses  or  other  predisposing  conditions  that  the  disease 
manifests  itself;  or  it  may  happen  that  only  strangers  and 
non-acclimated  inhabitants  incur  the  disease.  It  has  been 
suggested  that  this  immunity  is  probably  brought  about 
by  the  very  gradual  introduction  into  the  body  of  the  dis- 
ease germs  and  their  poisons,  so  that  old  residents  are  not 
susceptible  to  the  small  numbers  or  quantities  of  these 
which  are  sufficient  to  give  rise  to  the  symptoms  of  the 
particular  diseases  in  newcomers. 

It  is  sometimes  difficult  to  determine  just  when  or  how 
a  water-supply  has  been  infected  with  pathogenic  organ- 
isms, but  recently  it  has  been  shown  that  a  person  who 
has  recovered  from  a  transmissible  malady  may  continue 
to  carry  al)Out  in  his  body  and  excrete  the  disease  germs 
for    a    long  time.     Thus  the    bacteria    of  typhoid    fever 

'  For  a  long  time  the  belief  that  malaria  is  very  frequentlj',  if  not 
most  often,  transmitted  by  the  drinking-water  has  been  held  by  many 
sanitarians,  and  there  has  seemed  to  be  mnch  circumstantial  evidence  to 
substantiate  this  opinion.  Comparatively  recently,  however,  careful 
scientific  investigation  has  proved  that  this  disease  can  be  and  usually  is 
due  to  direct  inoculation  by  at  least  one  species  of  mosquito,  which  acts 
as  an  intermediary  host  in  the  life  cycle  or  development  of  the  malarial 
organism  (plasmodium  malaria;),  and  some  have  gone  so  far  as  to  say  that 
tlie  disease  is  probably  only  transmitted  in  this  way.  While  admitting 
the  force  of  these  arguments  and  evidence,  and  accepting  the  mosquito 
theory,  the  writer,  for  the  present  at  least,  is  not  convinced  that  the 
drinking-water  cannot  and  does  not  also  sometimes  serve  as  a  means  of 
transmitting  the  disease,  either  by  actiug  as  a  carrier  of  the  infected 
ova,  larvff;,  or  dead  bodies  of  mosquitoes,  or  by  directly  transferring  the 
malarial  organisms  from  what  has  long  been  considered  to  be  their 
natural  habitat — swamps  and  marshes. 


TRANSMISSION  OF  INFECTION  BY   WATER.     175 

may  be  found  in  the  urinary  secretion  of  a  large  propor- 
tion of  those  who  have  had  that  disease  for  as  long  as 
eight  or  ten  months  thereafter,  and  Levy  and  Kayser  have 
reported  a  case  where  these  organisms  were  found  in  the 
gall-bladder  of  a  woman  three  years  after  the  typhoidal 
illness.  It  is,  therefore,  easy  to  comprehend  how  such  a 
person,  going  from  place  to  place,  might  infect  not  one, 
but  many  sources  of  water-supply. 


Location. 

Date. 

Population. 

Cases. 

Deaths. 

1872 
1879 
1885 
1903 
1903  and  1904 

780 
5,800 
8,000 
13,000 
18,000 

144 

352 

1,104 

1,3U0 

1,348 

CatLTliam,  England. 

Mvinouth,  Pa 

Ithaca.  N.  Y 

Butler,  Pa 

21 
114 

78 
lU 

Many  in.stances  have  been  recorded  which  practically 
prove  the  transmissibility  of  infectious  diseases  by  means 
of  drinking-water,  and  of  these,  reference  may  be  made 
to  the  epidemics  of  typhoid  fever  at  Lausen  ^  in  Switzer- 
land, at  Plymouth,  Pa.,"  Butler,  Pa.,  and  Ithaca,  N.  Y.; 
of  malaria  on  board  the  transport  ship  "  Argo "  ;  ^  and 
of  cholera  in  London.*  The  writer  himself  had  an  oppor- 
tunity of  investigating  an  epidemic  of  ty]ihoid  fever  in  a 
small  village  in  North  Carolina.^  In  this  there  were 
only  four  or  five  in  about  sixty  cases  which  were  not  un- 
doubtedly due  to  contamination  of  the  subsoil-water  by 
the  infected  excreta  from  the  first  case  ;  and  of  four  of 
tlic  exceptions  (which  were  in  one  family),  the  first  was 
in    all    probability  infected    by  using  the  water  while  in 

^  Pepper's  System  of  Medicine,  vol.  1.,  p.  250. 

2  Eohe's  Text-book  of  Hygiene,  2d  edition,  p.  63. 

'Parkes'  Hygiene,  8th  edition,  p.  64,  and  Rohe,  p.  60. 

*Eohe,  p.  64.  ^  University  Medical  Magazine,  May,  1892. 


176  WATEB. 

attendance  upon  sick  neighbors,  and  the  others  by  direct 
contagion  from  the  first.  It  was  also  shown  that,  with 
the  exception  of  these  four,  the  cases  all  developed 
directly  along  the  lines  of  natural  drainage  leading  from 
the  residence  of  the  original  case — a  boy,  who  came  to  the 
village  sick  wdtli  the  disease — and  that  the  latest  cases  to 
develop  were  those  most  remote  from  the  starting-point 
of  the  infection. 

Moreover,  in  most  large  cities  of  this  and  other  countries 
the  typhoid  fever  death-rate  is  accepted  as  the  direct  index 
of  the  character  of  the  water-supply,  and  it  seems  to  be  a 
fact  almost  without  exception  that  any  marked  improve- 
ment in  the  latter  will  be  followed  by  an  immediate  and 
positive  reduction  in  the  former.  (See  chart  on  page  165.) 
The  same  may  also  be  said  to  hold  good  in  regard  to  diar- 
rhoeal  diseases ;  while  in  eastern  North  Carolina  there  has 
been  a  marked  reduction  in  the  prevalence  of  so-called 
malarial  fevers,  which  are  probably  para-typhoid  in 
reality,  as  a  result  of  the  efforts  of  the  State  Board  of 
Health  to  persuade  the  people  to  substitute  rain-water 
or  deep  well-water  for  the  subsoil-water  which  was  almost 
universally  used  a  few  years  ago. 

The  ova  of  certain  parasites,  such  as  tapeworms  or 
round-worms,  may  often  be  taken  into  the  system  with 
the  drinking-water,  and  these  upon  developing  may  cause 
disturbances  that  may  require  more  than  the  sliglit  atten- 
tion usually  given  to  them.  Any  attack  of  convulsions 
in  a  child  or  other  severe  manifestation  of  reflex  action 
should  lead  to  the  inquiry  as  to  whether  these  parasites 
may  not  be  present,  and  whether  tlu;  water-supply  has  not 
been  the  source  of  invasion. 

It  is  now  known  that  the  parasite  of  ankylostomiasis 
or  hook-worm  disease  may  also  be  carried  by  and  intro- 
duced into  the  human  Ijody  l)y  the  drinking  water. 


PARASITIC  DISEASES.  177 

Regarding  the  foregoing  remarks,  Parkes  makes  the 
following  statements  :  "1.  An  epidemic  of  diarrhoea  in  a 
community  is  almost  always  owing  to  either  impure  air, 
impure  water,  or  bad  food.  If  it  aifects  a  number  of 
persons  suddenly,  it  is  probably  owing  to  one  of  the  last 
two  causes,  and  if  it  extends  over  many  families,  almost 
certainly  to  water.  But  as  the  cause  of  the  impurity  may 
be  transient,  it  is  not  easy  to  find  experimental  proof. 
2.  Diarrhoea  or  dysentery  constantly  affecting  a  com- 
munity, or  returning  periodically  at  certain  times  of  the 
year,  is  far  more  likely  to  be  produced  by  bad  water  than 
by  any  other  cause.  3.  A  very  sudden  and  localized 
outbreak  of  typhoid  fever  or  cholera  is  almost  certainly 
owing  to  the  introduction  of  the  poison  by  water.  4.  The 
same  fact  holds  good  in  malarial  fevers,  and,  especially  if 
the  cases  are  very  grave,  a  possible  introduction  by  water 
should  be  inquired  into.  5.  The  introduction  of  the  ova 
of  certain  entozoa  by  means  of  water  is  proved  in  some 
places,  probable  in  others.  6.  Although  it  is  not  at  pres- 
ent possible  to  assign  to  every  impurity  in  water  its  exact 
share  in  the  production  of  disease,  or  to  prove  the  precise 
injfluence  on  public  health  of  water  which  is  not  extremely 
impure,  it  appears  certain  that  the  health  of  a  community 
always  improves  when  an  abundant  and  pure  water-supply 
is  given ;  and,  apart  from  this  actual  evidence,  we  are 
entitled  to  conclude  from  other  considerations  that  abun- 
dant and  good  water  is  a  prime  sanitary  necessity."  The 
statistics  already  given  and  those  to  come  in  later  pages 
arc  confirmatory  of  the  correctness  of  this  last  assertion, 
and  sanitary  authorities  now  realize  that,  in  addition  to 
the  mortality  from  typhoid  fever,  the  main  cause  of  an 
increase  in  the  death-rate  from  diarrhoeal  diseases  is  more 
often  to  be  fairly  attributed  to  a  contaminated  water-supply 

12 


178  WATER. 

than  to  improper  food  or  untoward  temperatures.  Even 
with  respect  to  cholera  infantum  (which  is  generally  sup- 
posed to  be  principally  due  to  the  influence  of  excessive 
heat  upon  the  infant  and  its  food)  a  number  of  epidemics 
show  a  closer  relation  to  impure  water-supply  than  to  tem- 
perature-changes. 

The  Purification  of  Water. — Impurities  in  water  may 
be  either  solid  matters  in  suspension  or  dissolved  sub- 
stances, and  may  be  organic  or  inorganic.  Any  turbidity 
is  due  to  solid  particles,  and  water  free  from  these  is  clear, 
though  it  may  be  colored  more  or  less  deeply  by  dis- 
solved matters.  But  a  clear  water  may  contain  such 
solid  bodies  as  bacteria,  ova  of  parasites,  etc.,  which  are 
too  minute  to  be  seen  with  the  naked  eye.  Whether 
harmful  or  not,  all  impurities  should  be  removed  in  so 
far  as  is  possible  from  all  supplies  of  drinking-water. 
This  may  be  done  to  a  considerable  extent  with  large 
volumes  of  water  before  distribution  to  consumers,  and 
should  always  be  attended  to  by  the  latter  if  the  water 
is  not  already  clean  and  within  the  limits  of  safety  when 
they  receive  it.  In  fact,  a  large  city  at  the  present  time 
can  scarcely  have  a  more  important  subject  for  considera- 
tion tlian  that  of  obtaining  the  purest  possible  water-supply 
for  its  people.  There  M'ill  always  be  a  tendency  among 
many  to  allow  matters  to  continue  as  they  are  or  as  they 
have  been  in  the  past,  and  a  decided  objection  by  others 
to  iiKMii-ring  additional  expense  for  what  may  seem  to  them 
only  aesthetic;  reasons ;  but,  no  matter  what  may  be  the 
cost  of  providing  a  reasonable  supply  of  pure  water  for 
any  large  city's  personal  and  domestic  uses,  a  very  little 
consideration  will  show  tliat  such  expenditure  is  true 
economy  from  solely  a  financial  point  of  view,  even 
tliough  we  ignore  the  misery  and  sorrow  of  the  sickness 


PURIFICATION  OF   WATER. 


179 


and    deaths    that    are    due    to    the    use    of    a   polluted 
water. 

As  has  been  stated  by  the  excellent  authority  quoted 
above,  "  the  health  of  a  community  always  improves 
when  an  abundant  and  pure  water-supply  is  given. 
The  death  of  3400  persons  from  cholera  followed  the 
temporary  supply  of  unfiltered  water  l)y  the  East  London 
Water  Company  in   1866,  while  the  rest  of  Loudon  re- 

FiG.  35. 


Portion  of  the  boundary  line  between  Hamburg  and  Altona.    The  dots 
indicate  cases  of  cholera.    (Harbixgton.) 

mained  nearly  free  from  the  disease  ;"  and  in  1892  "Ham- 
burg lost  8605  citizens  from  the  same  disease  alone," 
regarding  wdiich  "  the  health  authorities  found  that  the 
principal  cause  of  this  epidemic  was  the  polluted  w^ater- 
supply,"  ^  while  the  neighboring  city  of  Altona,  which  used 
filtered  water,  was  comparatively  free  from  the  disease. 
Again,  after   the    scourge    of  typhoid   fever   in   Ply- 

^  Hazen,  Filtration  of  Public  Water-supplies,  1895. 


180  WATER 

mouth,  Pa.,  in  1885,  when  there  were  1104  cases  and 
114  deaths  within  a  few  weeks  in  a  population  of  8000 
as  a  result  of  pollution  of  the  water-supply  by  a  single 
person,  great  care  was  taken  to  determine  the  exact  cost 
of  the  "  visitation  "  as  some  would  term  it.  It  was  found 
that  the  actual  expenditure  for  the  care  of  the  sick 
was  $67,100.17;  loss  of  wages  by  those  recovering, 
S30,020.08;  a  total  of  $97,120.25,  to  which  should  be 
added  a  number  of  times  the  $18,419.52  that  those  who 
died  were  earning  per  annum  when  taken  sick.  How 
much  cheaper  in  comparison  would  a  protecting  filter- 
plant  have  been  !  But  overlooking  sjiecial  epidemics,  and 
considering  the  average  annual  typhoid  death-rates  of  our 
cities,  we  find  that  experience  both  here  and  abroad  shows 
that  with  a  pure  water-supply  a  maximum  death-rate 
from  this  disease  is  25  jDcr  100,000,  and  that  any  city 
may  reasonably  expect  to  secure  even  a  lower  rate  by 
observing  proper  precautions.  And  yet  only  eight  cities 
of  over  50,000  population  whose  mortality  returns  were 
given  in  the  United  States  Census  Keports  of  1890  had 
so  low  a  figure.  On  the  other  hand,  there  were  five  cities 
of  over  (and  two  of  less  than)  50,000  that  had  100  or 
more  deaths  per  100,000,  all  seven  using  unfiltered  river- 
water.  The  remaining  fijrty-one  of  those  above  50,000 
had  rates  varying  from  20  to  98.  Counting  each  death 
as  a  loss  to  the  community  of  $5000 — not  an  excessive 
estimate  according  to  the  finding  of  courts  in  cases  of 
death  by  accident,  and,  inasmuch  as  most  typhoid  cases 
occur  during  the  working  age  of  from  fifteen  to  fifty  years — 
"  the  saviuiT  due  to  filtration  "  on  the  unnecessarv  deaths 
from  typhoid  fever  "  wouUl  have  paid  for  the  entire  cost 
of  filters  in  the  first  vear  thev  were  in  use"  in  the  first 


FINANCIAL  LOSS  DUE  TO  DISEASE.  181 

seven  of  these  cities ;  "  in  sixteen  others,  with  an  aggre- 
gate population  of  3,717,560,  filtration  would  have  paid 
for  itself  in  two  years  or  less,"  and  in  "  eighteen  others 
with  an  aggregate  of  3,238,617,  filtration  would  have 
saved  seven  or  more  lives  per  100,000  annually,  and 
would  have  more  than  paid  for  the  interest  and  cost  of 
operating  the  filters."  ^ 

Lawrence,  Mass.,  with  a  population  of  44,654  in  1890, 
built  a  filter  at  a  cost  of  $67,000,  and  saved  enough  lives, 
at  $5000  per  head,  to  pay  for  it  within  the  first  four 
months  that  it  was  in  use,  and  had  a  reduction  of  almost 
60  per  cent,  in  the  typhoid  death-rate  Avithin  a  year. 
In  Chicago,  when  the  similarly  estimated  loss  from 
typhoid  deaths  in  the  city  and  suburbs  amounted  to  over 
$10,000,000  in  1891,  the  abandoning  of  a  shore  inlet  near 
the  mouth  of  the  sewage-polluted  Chicago  River  in  1892 
resulted  in  a  reduction  of  60  per  cent,  in  the  typhoid 
mortality  during  the  following  year.  Albany,  N.  Y.,  is 
also  said  to  have  reduced  the  death-rate  from  this  disease 
70  per  cent,  since  the  installation  of  its  filter-plant. 

But  it  is  only  when  one  realizes  that  an  increase  in  the 
mortality  from  any  cause  of  only  1  in  1000  of  population 
means  1000  additional  deaths  per  annum  in  a  city  of  a 
1,000,000,  that  he  can  appreciate  the  meaning  and  the 
loss  in  capitalization  to  the  municipality  of  the  exceedingly 
high  typhoid  mortality  that  obtains  in  some  of  our  large 
cities.  At  the  valuation  of  $5000  per  capita,  and  consid- 
ering only  the  excess  above  the  maximum  typhoid  mor- 
tality of  a  pure-water  city,  this  death-loss  in  one  city  alone 
lor  several  years  has  amounted  to  upward  of  $500,000 
annually,  while  in  another  municipality,  with  an  average 
'  Hazeu,  Filtration  of  Public  Water-supplies. 


182  WATER. 

population  of  about  one-tliird  of  a  million,  the  excessive 
typhoid  deaths  above  a  25-per-100,000  rate  in  five  years 
(1900-1904)  amounted  to  the  astounding  total  of  1888, 
representing  in  capitalization  at  the  above  life  valuation 
the  sum  of  $9,440,000.  Nor  must  it  be  forgotten  that 
these  figures  do  not  include  the  cost  of  medical  attention 
and  nursing  for  the  thousands  who  were  sick,  nor  the  loss 
of  time  and  employment  by  those  who  recovered,  nor  do 
they  consider  the  financial  loss  due  to  sickness  and  deaths 
from  diseases  other  than  typhoid  fever  that  may  be  fairly 
attributed  to  polluted  water-supplies.  Can  anyone  doubt 
where  true  municipal  economy  lies,  and  is  there  not 
abundant  opportunity  for  sanitary  education  and  work  in 
this  direction  alone  for  many  years  to  come  ?  ^ 

Purification  before  distribution  may  be  by  either  or  all 
of  three  methods:  subsidence,  chemical  treatment,  and 
filtration. 

Subsidence. — The  first  method  consists  in  allowing 
the  water  to  stand  in  large  reservoirs  until  the  greater 
part  of  the  suspended  matters  have  fallen  to  the  bottom. 
If  sufficient  time  be  given,  much  of  the  organic  matter, 
whether  solid  or  dissolved,  will  be  decomposed  or  reduced 
to  simpler  compounds  by  the  action  of  the  sunlight,  oxy- 

1  According  to  the  special  Mortality  Report  of  the  U.  S.  Census  Office 
for  1900-1904,  the  deaths  from  typhoid  fever  in  the  "  registration  area" 
in  the  five  years  numbered  r)3,857,  of  which  41,078  were  in  cities,  and 
2r,,949  in  cities  of  100,000  population  or  over;  moreover,  50  cities  of 
less  than  100,000  population  had  rates  of  100  per  100,000  in  one 
or  more  years  of  the  five.  The  typlioid  death-rate  for  the  entire  "reg- 
istration area"  dropped  from  35.9  per  100,000  in  1900  to  32  in  1904,  and 
the  average  for  the  half-decade  was  33.8.  This  is  higher  than  that  of  any 
European  country  except  Italy,  the  rate  for  England  and  Wales  for  1903 
being  10 ;  for  Germany,  G.9,  and  for  Norway,  (5.4  per  100,000. 


PURIFICATION  IN  RESERVOIRS.  183 

gen,  animalculse,  saprophytes,  etc.  Most  of  the  bacteria 
also,  especially  the  pathogenic  species,  will  disappear 
either  by  sedimentation,  by  death  from  lack  of  favorable 
conditions,  or  on  account  of  the  germicidal  eifect  of  the 
sunlight.  Consequently,  a  water  originally  quite  impure 
may  be  much  improved  by  this  method  alone,  while  if  it 
is  used  in  conjunction  with  and  preliminary  to  filtration  it 
will  be  additionally  advantageous  in  that  it  reduces  the 
cost  of  the  latter  by  lessening  the  frequency  and  expense 
of  cleaning  the  filters. 

What  the  capacity  of  the  reservoirs  and  the  time  of 
storage  should  be,  depend  on  circumstances.  If  it  is  the 
only  method  of  purification  employed,  and  especially  if 
the  water  is  very  foul,  the  longer  the  time  of  storage  the 
better.  Again,  if  the  source  of  supply  is  variable  in  out- 
put or  if  it  is  liable  to  excessive  pollution  for  limited 
periods,  the  capacity  should  be  such,  if  possible,  that 
water  need  not  be  collected  during  the  emergency.  On 
the  other  hand,  if  the  water  is  to  be  subsequently  filtered, 
the  capacity  of  the  reservoirs  and  time  of  storage  need  not 
be  so  great.  Most  German  authorities  on  filtration  hold 
that  preliminary  sedimentation  for  twenty-four  hours  or 
even  less  is  sufficient,  most  of  the  solid  matters  being  pre- 
cipitated within  that  time,  if  at  all,  and  the  filters  being 
relied  upon  to  remove  the  remainder,  especially  the  finer 
particles  and  the  bacteria.  The  English  practice  is  to  store 
the  water  for  a  longer  time,  though  local  causes  related 
to  the  source  of  supply  are  the  reason  for  this.  Thus  the 
Lea  and  Thames,  from  which  the  London  companies  take 
much  of  their  water,  are  subject  to  extra  pollution  in 
times  of  flood,  which  are  usually  of  short  duration,  and  a 
sufficient  reserve  for  such  periods  is  of  obvious  value. 


184  WATER. 

All  storage  reservoirs  slionkl,  of  course,  be  kept  free 
from  extraneous  contamination,  and  should  be  cleaned 
from  time  to  time.  This  necessitates  an  arrangement  in 
pairs  or  groups,  or  a  partitioning  of  large  reservoirs,  so 
that  one  part  may  be  cleansed  without  putting  the  rest  out 
of  service.  Weeds  should  be  destroyed,  as  they  sometimes 
give  an  unpleasant  taste  to  the  water.  The  water  may  also 
have  a  bad  taste  or  odor  from  algse  and  other  species  of 
minute  plants,  which  especially  favor  a  pure  water  ex- 
posed to  sunshine.  They  are  not  known  to  be  harmful, 
but  it  may  be  necessary  to  cover  the  reservoirs  to  get  rid 
of  them  and  their  unpleasant  properties. 

Chemical  Treatment. — Where  a  water  is  very  hard 
or  contains  an  excess  of  mineral  matter  it  is  frequently  of 
advantage  to  treat  it  chemically.  If  the  hardness  is 
due  to  calcium  bicarbonate  in  excess,  it  may  be  re- 
moved by  the  addition  of  a  solution  of  calcium  hydroxide 
to  the  water,  insoluble  calcium  carbonate  being  formed 
and  precipitated.  The  change  is  represented  by  the 
equation : 

CaH2(C03)j+Ca(OH)j=2CaC03+2H20. 

Clark's  process,  based  on  this  reaction,  is  as  follows : 
Aljont  fourteen  or  fifteen  hundred-weight  of  lime  is 
allo\ved  to  eacli  million  gallons  of  water,  the  actual  quan- 
tity of  lime  depending  on  the  amount  of  bicarbonate  in 
the  water.  The  lime  is  slaked  in  a  tank  into  wliich  the 
water  to  be  treated  flows ;  the  mixture  is  well  stirred  and 
then  allowed  to  stand  for  twelve  hours,  when  the  siq^erna- 
tant  water  is  drawn  off,  the  tank  cleaned,  and  the  process 
repeated.  The  water  is  not  only  softened  in  this  way,  but 
the  precipitate  also  usually  carries    down  with   it  much 


CHEMICAL   TREATMENT  OF  WATER.  185 

of  the  solid  impurities  and  organic  matters  in  the  water. 
This  process  is  extensively  used  in  England,  where  much 
of  the  available  water  is  derived  from  the  underlying 
chalk-beds,  and  thus  has  a  superabundance  of  the  bicar- 
bonate ;  but  the  writer  is  unaware  that  it  finds  any  general 
application  in  this  country,  though  it  might  be  an  advisa- 
ble method  of  treatment  in  certain  of  our  limestone  dis- 
tricts. 

If  alum  (aluminum  sulphate)  be  added  to  an  impure 
water,  a  decomposition  of  the  salt  occurs,  the  acid  portion 
combining  with  the  bases  in  the  water  and  forming  a 
flocculent  precipitate  of  insoluble  basic  sulphates  and 
aluminum  hydroxide,  which  entangles  in  it  and  carries 
down  the  suspended  impurities  in  the  water,  beside 
removing  much  of  the  dissolved  organic  and  coloring 
matters.  Moreover,  careful  experiments  have  shown  that 
the  addition  of  only  about  one  grain  of  alum  per  gallon, 
followed  by  thorough  agitation  and  subsequent  settling 
for  twenty-four  hours,  will  almost  invariably  give  a  water 
free  from  germs  and  one  that  will  tend  to  remain  sterile 
for  a  considerable  time  ;  this  possibly  being  due  to  re- 
moval of  the  food-supply  of  the  bacteria.^ 

The  use  of  alum  is  especially  advantageous  when  a 
water  contains  a  very  fine  silt  or  the  like  in  suspension, 
and  which  is  not  removed  by  subsidence  even  after  a  con- 
siderable time.  It  is  also  to  be  used  in  conjunction  with 
or  preliminary  to  mechanical  filtration,  which  latter,  at  the 
usual  rate  of  operation,  is  oftentimes  practically  depend- 
ent upon  alum  for  the  furnishing  of  a  clear  safe  water. 
Comparatively  little  alum   is   needed,  even  with  a  very 

1 V.  and  A.  Babes,  Centralblatt  fiir  Bakteriologie  und  Parasiteukuude, 
1892,  vol.  xii.,  No.  45. 


186  WATER. 

dirty  water — usually  not  more  than  one  or  two  grains 
per  gallon,  and  if  the  supply  is  practically  adjusted  to 
the  condition  of  the  water,  as  it  should  be,  the  extremely 
minute  quantity  of  free  alum  that  may  sometimes  pass 
through  the  filters  is  harmless  and  unimportant. 

Should  the  water  be  lacking  in  sufficient  bases,  which, 
however,  is  extremely  improbable,  it  might  contain  when 
filtered  a  very  little  free  acid,  which  can  be  readily  neu- 
tralized by  the  addition  of  a  correspondingly  small  quan- 
tity of  sodium  hydroxide  or  carbonate,  the  resulting  salt 
affecting  neither  the  healthfulness  nor  the  palatability  of 
the  water.  It  has  been  suysrested  that  the  alum  be  first 
decomposed  by  the  addition  of  sodium  hydroxide,  then 
washed  free  from  the  resulting  sodium  sulphate  and  the 
flocculent  aluminum  hydroxide  added  to  the  water,  thus 
avoiding  the  chance  of  there  being  either  free  alum  or 
acid  in  the  cleared  water ;  but  experiments  show  that  the 
results  are  not  so  good  as  when  alum  alone  is  used. 

Regarding  the  danger  from  the  use  of  water  purified 
by  the  addition  of  alum,  Hazen  says  :  "  Although  alum 
in  large  quantities  is  undoubtedly  injurious  to  health,  it  is 
neitlior  a  violent  nor  a  cumulative  poison  ;  and  the  propo- 
sition that  one  })art  of  alumina  in  a  million  parts  of  water 
is  injurious  to  health  must  be  regarded  as  conjecture  rather 
than  :is  a  matter  of  proof  or  even  of  probability." 

The  Anderson  process,  which  consists  in  agitation  of 
(lie  water  with  metallic  iron  before  filtration,  has  been 
cinployed  at  Antwerp  and  elsewhere;  but  it  is  not  clear 
that  with  large  quantities  of  water  better  results  are  ob- 
tained than  by  simple  filtration.  The  idea  is  that  some 
of  the  iron  is  converted  into  soluble  ferrous  carbonate, 
which  then  oxidizes  to  insoluble  ferric  hydroxide  and 
carries  down  with  it  the  suspended  and  many  dissolved 


FILTRATION.  187 

impurities,  and  thus  facilitates  their  removal  by  sedimen- 
tation and  filtration.  The  difficulty  in  using  this  process 
on  a  large  scale  seems  to  be  that  the  carbonate  is  not 
formed  quickly  enough,  and  also  that  too  much  of  the 
iron  may  remain  in  solution  even  after  filtration. 

Filtration. — For  the  purification  of  large  quantities  of 
water,  such  as  are  needed  for  great  cities,  there  can  be  no 
question  that  sand  filtration  is,  in  the  majority  of  cases, 
the  most  available,  satisfactory,  and  efficient  method, 
though  it  may  often  be  advantageously  preceded  by  sedi- 
mentation or  by  chemical  treatment,  as  already  described. 
The  former  especially,  by  removing  much  of  the  suspended 
matter,  will  prolong  the  use  of  the  filters  between  clean- 
ings and  thus  materially  lessen  the  cost  of  maintenance  ; 
while  the  latter  may  greatly  improve  the  chemical  quality 
of  the  filtered  water. 

Municipal  filters  of  the  type  to  be  described  are  as  yet 
not  widely  nor  sufficiently  well  known  in  this  country,  but 
they  have  been  used  abroad  with  increasingly  good  results 
for  uj)ward  of  half  a  century,  and  they  now  furnish  the 
daily  supply  of  water  to  more  than  twenty  millions  of 
people.  However,  we  may  take  credit  in  the  knowledge 
that  the  most  thorough  and  scientific  investigation  of  their 
action  and  efficiency  has  been  made^  on  this  side  of  the 
Atlantic,  under  the  auspices  of  the  Massachusetts  State 
Board  of  Health,  and  that  it  is  to  this  body  that  wd  are 
indebted  for  much  of  the  positive  information  that  we 
now  have  concerning  them. 

The  limitations  of  this  work  do  not  permit  a  full  dis- 
cussion of  the  principles  or  merits  of  such  filters,  but  the 
following  details  are  given  that  the  reader  may  appreciate 
the  simplicity  of  their  construction  and  the  efficiency  of 
their  work.     Those  desiring  more  extended  information 


i: 


WATER. 


are  referred  to  the  Massachusetts  reports  that  discuss  this 
sulrject,  and  to  the  excellent  work  of  Hazen,  already 
mentioned/  from  which  many  of  the  accompanying  state- 
ments and  illustrations  have  been  taken. 

Almost  without  exception  these  filters  now  consist  of  a 
layer  of  clean  sand  of  a  certain  degree  of  fineness  spread 
upon  a  layer  of  gravel  in  a  carefully  prepared  basin,  the 
whole  being  under-drained  and  proper  arrangements  made 

Fig.  36. 


Supply  to  Filters 


ISujtply   to  Filiera 

Plan  of  filter-beds  at  Albany,  N.  Y. 


for  the  controlling  of  the  depth  of  water  upon  the  surface, 
rate  of  flow  of  the  filtrate,  cleaning  of  filters,  etc.  (Fig. 
33.)  Such  filters  act  primarily  as  strainers  to  remove  the 
solid  impurities  from  the  water,  but  their  efficiency  is 
much  increased  by  the  sediment  that  is  retained  upon 
the  surface  of  the  sand  and  that  forms  a  filter  or 
"blanket"  much  finer  than  the  latter  and  is  capable  of 
mechanically  preventing  the  passage  of  most  of  the 
1  Filtration  of  Public  Water-supplies. 


FUNCTIONS  OF  SEDIMENT-LAYER. 


189 


bacteria  always  present  in  a  surface-water.  Moreover,  this 
removal  of  the  bacteria  is  often  largely  due  to  the  organ- 
isms themselves  in  the  sediment-layer,  because  by  forming 
a  felt-like  growth  therein  they  not  only  increase  the  fine- 
ness of  the  strainer,  but  by  acting  as  saprophytes  they 
also  decompose  much  of  the  organic  matter  and  even  kill 
the  pathogenic  bacteria.  However,  it  now  seems  probable 
that  for  continuous  filters  the  action  is  sometimes  mainly 
mechanical,  consisting  in  the  removal  of  suspended  mat- 
ters and  bacteria,  and  but  slightly  affecting  the  dissolved 
organic  matters.  On  the  other  hand,  in  intermittent  fil- 
tration, where  the  conditions  more  nearly  resemble  those 

Fig.  37. 


AU.BAJK  KOT£  C^ 


General  arrangement  of  filter-plant.    (Hazen.) 

in  the  natural  soil  and  where  the  filters  are  periodically 
aerated,  the  straining  action  is  less  perfect  on  account  of 
the  greater  rate  of  filtration  necessary,  but  the  nitrifica- 
tion and  destruction  of  organic  matter  due  to  the  action 
of  the  saprophytes  and  oxygen  are  greater.  Intermittent 
filters,  therefore,  will  probably  prove  to  be  the  better  for 
tlie  purification  of  sewage  or  a  very  impure  water,  though 
usually  their  efficiency  in  removing  bacteria  seems  to  be 
inferior  to  that  of  continuous  filters. 

Where  a  water  contains  a  very  fine  sediment  or  silt  in 
large  quantities,  the  sand  bed  may  be  clogged  and  choked 
in  a  few  hours  and  before  there  is  time  for  the  formation 


190  WATER. 

of  the  bacterial  film  mentioned  above,  and  the  filtration 
must  be  more  mechanical.  For  example,  at  New  Orleans, 
where  the  Mississippi  River  contains  an  enormous  amount 
of  a  silt  so  fine  that  much  of  it  is  submicroscopic  and 
many  of  the  particles  even  smaller  than  bacteria,  the 
water  is  pumped  from  the  river  to  a  sedimentation  basin 
capable  of  holding  twenty-four  hours'  supply,  through 
which  it  passes  slowly,  leaving  the  coarser  and  heavier 
sediment ;  then  to  a  mixing  basin,  where  alum  is  added 
as  a  coagulant  to  an  extent  not  exceeding  six  grains  per 
gallon,  and  then  to  the  sand  filter-beds.  The  "  blanket" 
is  thus  formed  by  the  coagulum  due  to  the  alum  which 
commingles  with  and  holds  the  silt,  preventing  the  lat- 
ter from  entering  and  choking  the  filter.  The  filter-beds 
are  cleaned  daily  or  oftener  by  forcing  from  below  first  a 
liberal  washing  of  filtered  water  and  then  a  supply  of  air. 
The  cost  of  this  treatment  is  about  §600  per  day  for  a 
supply  of  40,000,000  gallons. 

The  location  of  the  filter-beds  with  respect  to  the 
source  of  supply  and  the  storage  reservoirs  wall  depend 
largely  on  local  conditions,  cost  of  pumping,  etc.  Settling 
basins  are  almost  essential  where  the  water  to  be  fil- 
tered is  very  turbid,  even  if  only  at  intervals.  Refer- 
ence has  already  been  made  to  the  difference  of  oj^inion 
between  English  and  Continental  authorities  regarding 
the  size  of  these  settling  basins.  As  the  filtration  does 
not  remove  hardness  due  to  dissolved  minerals,  it  may 
also  be  advisable  to  use  the  Clark  process  previous  to 
sedimentation  and  filtration.  Part  of  the  color  due  to 
peat  or  vegetable  matters  is  removed  by  ordinary  filtra- 
tion, and  still  more  may  sometimes  be  destroyed  by  the 
jirevious  addition  of  alum,  but  such  preliminary  treatment 
is  unusual.     Where  the  water  comes  from  a  lake  or  from 


CONSTRUCTION  OF  FILTER-BEDS. 


191 


a  river  with  a  slow  current,  settling  basins  are,  of  course, 
unnecessary. 

Inasmuch  as  it  is  needful  to  govern  the  depth  of  the 
water  upon  the  filter-beds  according  to  the  rate  of  flow 
desired,  the  thickness  and  resistance  of  sand,  etc.,  and  to 
jjrevent  disturbance  of  the  sand  and  sediment  layer  by 
the  force  of  the  entering  current,  some  method  of  regu- 
lating the  inflow  is  required.  The  accompanying  illus- 
tration shows  a  comparatively  simple  arrangement  for 
this  purpose.     (Fig.  38.) 


Fig.  38. 


20  Fest 

Regulation  of  inflow  used  at  Hamburg.    (Hazen.) 


The  total  area  of  the  filter-beds  will  depend  upon  the 
amount  of  water  supplied,  the  rate  of  filtration,  and  the 
proportion  of  area  out  of  use  while  being  cleaned.  The 
total  area  is  to  be  divided  into  beds,  varying  in  number 
according  to  circumstances,  so  that  one  or  more  of  these 
beds  may  be  cleaned  while  the  rest  are  in  use.  Large 
beds  decrease  the  cost  per  acre  on  account  of  less  masonry, 
etc.,  being  needed,  but  it  may  be  more  difficult  to  main- 
tain an  even  action  over  large  areas.     Evenness  of  action 


192 


WATER. 


is,  however,  largely  governed  by  the  size  and  arrangement 

of  the  under-drains. 

Fig.  39. 


Interior  of  a  covered  filter  ready  for  use. 

The  walls  and  bottoms  of  filter-beds  should  be  made 
water-tight,  that  there  may  be  no  waste  of  the  filtered 

Fig.  40. 


Sectional  plan  of  a  covered  filter. 


water  on  the  one  liand,  nor  any  ingress  of  foul  soil-water 
on  the  other.     The  form  of  the  filter-bed  is  immaterial. 


MATERIALS  FOR  FILTER-BEDS.  193 

provided  evenness  of  work  over  the  whole  area  is  not  im- 
paired. Where  the  mean  January  temperature  is  below 
the  freezing-point  the  beds  should  be  covered,  as  the  for- 
mation of  ice  upon  them  seriously  impairs  their  efficiency, 
and  as,  moreover,  a  number  of  epidemics  of  typhoid  fever 
and  certain  intestinal  diseases  seem  to  be  directly  traceable 
to  ice-formation.  This  may  have  been  on  account  of  the 
overtaxing  of  the  filters  through  increased  difficulty  in 
working,  or  because  the  sediment  layer  and  the  sand  were 
disturbed  in  the  removal  of  the  ice. 

As  already  stated,  the  materials  used  practically  every- 
where are  clean  sand  and  gravel,  and  the  sharper  the 
sand-grains  the  better.  At  the  Lawrence  Experiment 
Station  of  the  Massachusetts  State  Board  of  Health  "  the 
size  of  a  sand-grain  is  uniformly  taken  as  the  diameter  of 
a  sphere  of  equal  volume,  regardless  of  its  shape."  More- 
over, as  it  is  "  the  finest  portion  which  mainly  determines 
the  character  of  sand  for  filtration,"  the  effective  size  is 
taken  to  be  "the  size  of  a  grain  such  that  10  per  cent,  by 
weight  of  the  particles  are  smaller  and  90  per  cent,  are 
larger  than  itself."  As  uniformity  of  grain  is  also  im- 
portant, the  uniformity  coefficient  is  "  the  ratio  of  the  size 
of  grain  which  has  60  per  cent,  of  the  sample  finer  than 
itself  to  the  size  which  has  10  per  cent,  finer  than  itself." 
Obviously,  the  velocity  of  water  through  a  layer  of  sand 
will  depend  upon  the  effective  size  of  the  grain,  the  thick- 
ness of  the  layer  through  which  the  water  passes,  and  the 
loss  of  head  due  to  the  frictional  resistance  of  the  sand. 
A  rise  in  temperature  causes  a  progressive  increase  in 
velocity. 

The  effective  sizes  of  sand-grain  in  use  in  most  of  the 
foreign  filters  average  from   0.31   to  0.40  mm.     In  gen- 
eral, it  may  be  said  that  the  finer  the  sand  the  better  is 
13 


194  WATER. 

the  quality  of  the  normal  filtrate  and  the  less  the  danger 
of  an  unsafe  effluent  in  case  the  sediment  layer  on  top  of 
the  sand  is  broken  ;  but,  on  the  other  hand,  cost  of  filtra- 
tion increases  with  the  smallness  of  sand-grain,  since  the 
filters  must  be  cleaned  oftener  and  fine  sands  are  harder 
to  wash,  as  well  as  because  the  velocity  of  flow  is  slower 
through  fine  sands.  All  things  considered,  the  best  results 
will  probably  be  obtained  with  a  sand  having  a  uniformity 
coefficient  of  not  more  than  3 — the  lower  the  better — and 
an  effective  size  of  from  0.20  to  0.35  mm.,  the  latter 
depending  largely  upon  the  character  and  clearness  of 
the  water  to  be  filtered. 

The  thickness  of  the  sand  layer  should  be  such  that  it 
may  be  scraped  a  number  of  times  before  becoming  so 
thin  as  to  require  replacing.  The  German  Imperial  Board 
of  Health  requires  a  thickness  of  at  least  twelve  inches 
after  the  last  scraping ;  while  the  original  thickness  should 
be  from  twenty-four  to  forty-eight  inches,  the  thicker  the 
better,  provided  the  cost  of  the  filter  be  not  made  too 
great  and  the  rate  of  filtration  be  not  too  much  dimin- 
ished. The  sand  should  be  of  the  same  degree  of  fine- 
ness throughout. 

As  for  the  gravel  beneath  the  sand,  there  is  no  reason 
why  it  should  be  of  excessive  thickness.  A  depth  of  one 
foot  is  probably  sufficient,  provided  the  stones  are  of 
varying  size,  so  arranged  that  the  sand  above  will  not 
work  into  and  through  the  interstices,  and  that  the  water 
may  freely  enter  the  under-drains  at  low  velocity.  The 
loss  of  head  in  water  flowing  through  a  thin  layer  of 
gravel  jiroperly  placed  is  conqiaratively  slight.  Foreign 
fibers  do  have  a  gravel  layer  of  two  feet  or  more  in  thick- 
ness, as  a  rule,  but  careful  experiments  at  Lawrence, 
Mass.,  show  that  this  depth  is  unnecessary,  provided  that 


UNDEB-DBAINS  IN  FILTER-BEDS.  195 

the  gravel  is  properly  laid  as  indicated,  and  that  the 
under-drains  are  not  too  far  apart. 

The  under-drains  should  be  of  such  size  and  so  con- 
structed that  the  frictional  resistance  which  they  offer  to 
the  flow  of  the  water  is  only  a  small  percentage  of  that  of 
the  clean  sand,  and  that  the  rate  of  filtration  is  the  same 
over  the  whole  area  of  the  filter.  There  is  usually  a  main 
drain  along  the  middle  of  the  filter-floor  with  smaller  par- 
allel lateral  drains  leading  into  it  at  regular  intervals. 
The  drains  may  be  made  of  brick  with  open  joints,  or, 
for  the  laterals,  of  tile,  which  is  usually  cheaper.  Care 
must  always  be  had  that  the  openings  are  sufficient  in 
number  and  size  to  admit  the  water  freely. 

The  area  drained  should  vary  from  about  300  square 
feet  for  a  4-inch  lateral  drain  to  4400  square  feet  for  a 
12-inch  main,  the  velocity  of  flow  in  these  being  respec- 
tively 0.30  and  0.51  foot  per  second  ;  while  larger  drains 
should  have  a  cross-section  of  at  least  one-six-thousandth 
of  the  drained  area.  The  European  custom  of  ventilat- 
ing drains  by  means  of  pipes  passing  up  through  the  sand 
and  water  above  is  not  to  be  commended,  since  such  ven- 
tilation apparatus  is  unnecessary,  increases  the  cost  of  the 
filters,  and,  what  is  worse,  may  allow  impurities  to  con- 
taminate the  filtered  water  in  the  under-drains. 

Recently  it  has  been  suggested  that  the  filter-beds  be 
constructed  directly  over  the  storage  reservoirs  for  the 
filtered  water,  the  beds  being  supported  on  suitable  steel 
columns  resting  on  concrete  foundations  in  the  bottom  of 
the  reservoirs.  The  bottom  layer  of  the  filter,  composed 
of  gravel  or  broken  stone,  Avould  rest  on  steel  tubes  or 
bars  several  feet  above  the  level  of  the  water  in  the  reser- 
voir, thus  allowing  the  filtrate  to  be  aerated  as  it  falls 
through  the  intervening  space.     Theoretically,  it  would 


196 


WATER. 


seem  that  the  plan  is  a  good  one,  and  actual  results  indi- 
cate that  it  practically  is  so.  Some  of  the  advantages  are 
the  absence  of  under-drains  and  loss  of  the  resistance 
factor  due  to  them,  the  aeration  of  the  filtrate  as  indi- 
cated, and  also  the  practically  continuous  aeration  of  the 
filter-bed  itself,  thus  enabling  the  saprophytic  bacteria  in 
the  upper  layers  to  carry  on  their  work  of  oxidizing  and 
nitrifying    the   organic   impurities    of    the    water.      One 

Fig.  41. 


Simplest  form  of  regulating  outflow  from  filter-beds.    Stralau  filters  at 
Berlin.    (Hazen.) 

serious  objection  to  such  a  filter  is  that  an  accidental  over- 
flow would  contaminate  at  once  all  the  filtered  water  in 
tlie  storage  reservoir. 

Althougli  it  has  been  the  custom  to  keep  the  depth  of 
water  ujion  the  filter-beds  in  excess  of  the  loss  of  head, 
this  is  not  essential.  On  foreign  filters  the  usual  depth  is 
from  30  to  52  inches,  thougli  less  than  tliis  might  suffice 
in  many  instan(!es.  The  iKH^cssity  of  regulating  tlie  inflow 
and  outflow  and  of  maintaim'ng  a  constant  level  must  not 
be  overlooked  if  uniform  results  are  desired. 

Summarizing  the  preceding  statements,  the  loss  of  head 


RATE  OF  FILTRATION.  197 

and  rate  of  filtration  will  depend  upon  the  depth  of  water 
on  the  filters,  the  thickness  of  the  sand  layer,  size  of 
sand-grains,  resistance  of  under-drains,  temperature,  etc., 
and  all  these  will  likewise  affect  both  the  cost  and  the 
efficiency  of  the  filtration. 

Where  the  water  is  taken  directly  from  a  river,  or  if 
the  opportunity  for  sedimentation  has  been  brief,  2,000,000 
gallons  per  acre  per  day  will  probably  be  a  safe  rate  of 
filtration  to  maintain  continuously,  though  with  a  clear 
water  or  in  emergencies  a  rate  one-half  greater  will  very 
likely  not  materially  alter  the  quality  of  the  filtered  water 
or  increase  the  risk.  But  in  general  as  the  rate  increases 
the  efficiency  decreases.  However,  very  careful  and 
thorough  experiments  preliminary  to  the  construction  of 
the  Philadelphia  filters  have  shown  that  in  the  case  of 
some  waters,  at  least,  the  rate  may  safely  be  increased 
to  even  5,000,000  and  sometimes  to  almost  6,000,000 
gallons,  provided  the  water  be  first  passed  through  a  so- 
called  "  rough  filter "  made  of  such  materials  as  broken 
coke,  lumps  of  burned  clay,  etc.  Where  the  filters  are 
constructed  above  the  storage  reservoirs  in  the  manner 
heretofore  described,  it  is  claimed  that  much  larger  quan- 
tities of  water  may  be  filtered  in  a  given  time  with  equally 
good  results.  If  this  be  so,  it  is  probably  due  to  the  in- 
creased saprophytic  and  oxidizing  action  resulting  from 
the  continuous  aeration  of  the  filter. 

As  the  sediment  accumulates  and  deepens  upon  the  sur- 
face of  the  sand  the  rate  of  flow  necessarily  diminishes, 
and  it  becomes  necessary  after  a  time  to  remove  the  de- 
posit. This  is  done  by  carefully  scraping  off  the  top  layer 
of  the  sand  to  the  depth  of  from  one-half  to  one  and  one- 
half  inches,  repeating  the  scraping  as  often  as  may  be 
necessary  until  the  thickness  of  sand  above  the  underlying 


198  WATER. 

gravel  is  near  the  permissible  minimum.  Then  the  sand 
which  has  been  removed,  and  which  has  meanwhile  been 
thoroughly  washed  by  a  stream  of  the  filtered  water, 
driven,  if  necessary,  by  a  force-pump,  and  afterward  ex- 
posed for  some  time  to  the  action  of  the  sunlight  and  air, 
is  carefully  replaced,  packed,  and  levelled  upon  the  beds. 
These  do  not  again  attain  their  greatest  efficiency  until  a 
certain  amount  of  sediment  from  the  water  has  once  more 
collected  upon  them,  and  it  is,  therefore,  not  advisable  to 
use  the  filtered  water  for  some  time  after  the  cleaning 
and  until  bacteriological  tests  show  that  the  maximum 
purification  is  being  attained. 

An  essential  in  the  management  of  all  large  filters  is 
the  daily  bacteriological  and  chemical  examination  of  both 
the  filtered  and  unfiltered  water.  This  not  only  serves  to 
give  warning  of  any  accident  to  the  filter,  but  is  necessary, 
as  the  best  test  of  the  efficiency  of  a  sand  filter  is  the 
percentage  of  bacteria  which  it  takes  from  unfiltered 
water.  Unless  a  filter  is  holding  back  from  98  to  99  per 
cent,  or  more  of  the  bacteria,  it  needs  close  inspection, 
although  it  must  be  remembered  that  it  is  more  difficult 
to  get  good  results  with  a  badly  polluted  water  than  with 
one  that  is  comparatively  pure. 

Domestic  Purification  of  Water. — Boiling  destroys 
living  organisms  and  disease  germs  ;  it  also  drives  off  the 
carbon  dioxide  and  other  gases  of  the  water  and  causes 
the  precipitation  of  many  mineral  substances  held  in  solu- 
tion by  these  gases.  This  is  especially  the  case,  as  has 
been  stated,  wliorc  the  water  is  hard  from  the  presence  of 
calcium  bicarbonate  in  excess ;  but  iron  is  also  often 
thrown  down  by  boiling.  If  the  water  contains  a  very 
fine  sediment,  not  removed  by  settling  or  filtration,  it  may 
l)e  advantageous  to  add  a  little  alum  and  chalk  to  produce 
the    flocculent  precipitate    already  described.     Potassium 


DOMESTIC  PURIFICATION   OF   WATER. 


199 


permanganate  has  little  effect  in  purifying  a  foul  water. 
Agitation  with  iron  filings  may  do  a  little  good  by  favor- 
ing oxidation  of  organic  matters.  Tannin  is  believed  to 
destroy  micro-organisms,  and  a  harmful  water  may  some- 
times be  made  usable  by  boiling  with  tea-leaves  or  other 
astringents.     Citric  acid  is  said  to  destroy  algse  and  many 

Fig.  42. 


WATER    MAIN 


Wnter  sterilizer  for  schools,  factories,  etci  a,  Supply  pipe ;  h,  steam  coil; 
r,  thermometer;  er,  corrugated  and  perforated  metal  plates  ;  //,  air  openings 
guarded  by  cheese-cloth ;  4,  tap  to  admit  cooling  water  around  g  g,  the 
storage  tanks. 

kinds  of  bacteria.  Aeration  and  agitation  improve  a 
water  after  distillation  or  })oiling  by  restoring  oxygen  and 
also  by  oxidizing  organic  matters.  Remember  that  boiled 
water   is   prone   to  take  up   gases  of  any  kind,  whether 

1  From  the  Bulletin  of  the  Chicago  Health  Department,  Sept.  19,  1903. 


200 


WATER. 


impure  and  offensive  or  otherwise.  Organic  matters  are 
removed  by  boiling,  exposure  to  air,  agitation,  addition 
of  alum,  astringents,  charcoal,  etc. ;  calcium  bicarbonate, 
by  boiling  or  by  adding  caustic  or  slaked  lime  or  a  little 
sodium  hydroxide  or  sodium  carbonate ;  iron,  by  boiling 
and    by   adding   lime-water.     According  to  Parkes  and 

Fig.  43 


Section  of  domestic  still. 


Rideal,  fifteen  grains  of  acid  sodium  sulphate  to  the  pint 
(I  in  500)  will  destroy  tyi)hoid  bacilli  in  five  minutes. 
Calcium  and  magnesium  sulphates  and  chlorides  cannot 
readily  be  removed.  Some  plants  help  to  purify  by 
means  of  the  oxygen  which  they  give  to  the  water. 


THE  FORBES  STERILIZER.  201 

Distillation  gives,  of  course,  a  water  free  from  harmful 
impurities,  but  one  which  has  lost  its  gases,  and  which 
may  be  improved  in  palatability  by  aeration  or  by  being 
charged  with  carbon  dioxide  gas.  Stills  for  domestic  use, 
capable  of  supplying  an  abundance  of  water  for  drinking 
and  cooking  purposes,  can  now  be  purchased  at  moderate 
cost.  The  main  objection  to  distillation  in  the  household 
is  that  the  process  is  somewhat  slow  and  tedious. 

Comparatively  recently  an  apparatus  has  been  invented 
and  introduced  which  furnishes  a  boiled  water  free  from 
disease  germs,  yet  unchanged  in  taste  by  the  boiling,  and 
at  nearly  the  same  temperature  as  the  water  entering  the 
apparatus.  This  is  the  Forbes  (formerly  the  AVaterhouse- 
Forbes)  sterilizer.  The  principles  involved  in  its  con- 
struction and  operation  are  that  only  a  small  bulk  of 
water  is  being  boiled  at  any  instant ;  that  it  is  boiled 
for  only  a  very  short  time,  thus  preventing  loss  of  the 
original  gases  and  taste ;  that  all  disease  germs  are  killed 
by  the  boiling;  that  it  is  impossible  for  water  M'hich 
has  not  been  boiled  to  pass  through  the  apparatus  ;  and 
that  the  heat  of  the  boiled  water  is  used  to  warm  the 
unboiled  water  (thus  economizing  fuel)  at  the  same  time 
that  the  latter  is  made  to  cool  the  former. 

Reference  to  the  diagram  (Fig.  44)  shows  that  tlie  water 
can  rise  no  higher  than  the  level  A^  until  it  ''boils  over'' 
through  the  spout  a  into  the  receiver  h.  The  interchange 
of  heat  takes  place  through  the  diaphragm  c,  which  in  the 
apparatus  itself  is  very  thin  and  corrugated,  so  as  to 
expose  large  surfaces  to  the  water  on  the  two  sides  of  it. 

This  apparatus  is  furnished  in  a  suitable  size  for  house- 
Ji<»ld  use.  It  is  also  made  on  a  large  scale  and  in  a  con- 
venient form  for  transportation,  having  been  adopted  by 
the  United  States  Army  as  being  "  well  adapted  for  the 


202 


WATER. 


al)un(lant  supply  of  sterile  water  to  troops  in  the  field." 
The  Board  of  Medical  Officers  appointed  by  the  Surgeon- 
General  of  the  Array  to  consider  the  filters  and  other  ap- 
paratus of  the  kind  submitted  made  the  following  report: 
"  The  advantages  of  this  most  ingenions  water  steril- 

FiG.  44. 


Diagrammatic  representation  of  the  principle  of  the  Forbes  sterilizer. 

izer  arc  ;  First.  That  water  passing  through  it,  although 
brought  to  the  boiling-point,  is  maintained  at  this  tem- 
perature for  so  short  a  time  as  not  to  be  deprived  of  its 
naliiral  gases,  and  hence  not  rendered  unacceptable  to  the 
taste.  Second.  That  all  living  micro-organisms  .  .  . 
are  destroyed  by  the  degree  of  heat  attained  during  the 


THE  FORBES  STERILIZER.  .  203 

passage  of  the  water  tlirough  the  apparatus.  Third.  It 
furnishes  an  abundant  supply  of  practically  sterile  water, 
and  may  be  kept  in  action,  if  necessary,  for  the  entire 
twenty-four  hours  without  renewing  the  supply  of  oil  in 
the  reservoir,  and  at  a  cost  of  about  one-fourth  of  a  cent 
an  hour.  Fourth.  The  water,  having  been  slowly  heated 
until  it  reaches  temporarily  the  boiling-point,  is  afterward 
cooled  to  within  4  or  5  degrees  F.  of  the  water  entering  the 
apparatus.  This  is  one  of  the  important  advantages  pos- 
sessed by  this  sterilizer.  By  placing  the  bottom  of  the 
exchange  in  a  freezing  mixture  the  temperature  of  the  ster- 
ilized water  as  it  flows  from  the  machine  may  be  reduced 
below  40°  F.  Fifth.  Its  durability  and  freedom  from 
liability  to  breakage.  Sixth.  The  facility  with  which  the 
apparatus  may  be  put  together  and  entirely  taken  apart ; 
only  one  tool,  a  wrench,  being  required  for  this  purpose. 
Seventh.  The  facility  with  which  the  apparatus  can  be 
thoroughly  cleansed.  This  is  effected  by  the  removal  of 
the  rubber  cocks,  thus  permitting  a  complete  flushing  out 
of  both  exchanges.  The  fact  that  the  apparatus  does  not 
clarify  the  water  is  also  deemed  of  no  particular  impor- 
tance by  the  Board,  since  this  may  be  easily  effected  prior 
to  its  passage  through  the  sterilizer  by  means  of  one  or 
t\TO  water  barrels  partially  filled  with  fine  and  coarse  sand 
and  placed  at  a  proper  height  above  the  sterilizer.  As  a 
result  of  exhaustive  experiments  .  .  .  the  Board  is  of  the 
opinion  that  this  sterilizer  is  superior  to  all  filters  or  other 
water  sterilizers  submitted  for  trial.  AVe,  therefore,  after 
a  careful  consideration  of  the  requirements,  respectfully 
recommend  that  the  Forbes  sterilizer  be  issued  for  the  use 
of  troops  serving  in  the  field." 

House  filters  are  dangerous  unless  properly  cared  for, 
and   may  give  more  and  worse  impurities  to  the  water 


204 


WATER. 


than  they  take  from  it.  What  a  filter  takes  from  a  water 
is  left  in  the  filter  unless  otherwise  removed,  and  an  accu- 
mulation of  such  impurities  cannot  improve  the  water 
passing  through  them.  The  organic  matters  will  undergo 
decomposition  and  putrefaction,  and  will  furnish  a  good 
culture-medium  for  bacteria,  and  these,  together  with  the 
soluble  putrefaction-products,  will  in  most  cases  be  carried 
through  the  filter  with  and  by  the  filtered  water.  A  filter 
has  no  miraculous  power  to  annihilate  filth,  and  the  size 
of  a  filter  must  always  limit  the  work  it  can  do,  whatever 
the  materials  used. 

According  to  Parkes,  the  requisites  of  a  good  filter  are : 
1.  That  every  part  shall  be  easily  accessible  for  cleansing 

Fig.  45. 


Tubes  of  unglazed  porcelain  for  Pasteur  filter. 

or  renewing  the  medium.  2.  That  the  filtering  medium 
shall  have  suificient  purifying  power  and  be  present  in 
sufficient  quantity.  3.  That  the  medium  give  nothing  to 
the  water  favoring  the  growth  of  low  forms  of  life.  4.  That 
the  purifying  power  be  reasonably  lasting.  5.  That  there 
be  nothing  in  the  constru(ttion  of  the  filter  itself  capable 
of  undergoing  putrefaction  or  of  yielding  metallic  or  other 
imi)urities  to  tiie  water.  6.  That  the  filtering  material 
shall  not  clog,  and  that  the  flow  of  water  \w  reasonably 
rapid;  to  wlii(^h  may  be  added:  7.  That  the  filtering 
medium  be  sucli  that  it  can  be  readily  cleansed  and  ster- 
ilized, or  else  so  cheap  that  the  removal  and  replenishing 


HOUSE  FILTERS. 


205 


may  not  be  neglected  when  necessary  on  account  of  the 
expense. 

House  filters  may  be  divided  into  three  classes  :  (a) 
those  entirely  disconnected  from  the  water-supply  pipes 
of  the  house ;  (b)  those  connected  with  the  water-pipes, 
but  intended  to  filter  only  a  limited  quantity,  as  for  drink- 
ing, cooking,  etc. ;  (c)  those  connected  with  the  house  ser- 
vice-pipe and  intended  to  filter  all  the  water  used  in  the 
house.     The  same  filtering  media  may  be  used  in  all  three 

Fig.  46. 


Berkfeldt  filter  attached  to  tap. 


classes,  but  it  will  be  found  best  in  the  two  first  to  employ 
substances  through  which  the  water  passes  slowly,  while 
the  latter  class  must  necessarily  filter  the  water  more  rap- 
idly in  order  to  yield  a  sufficient  supply.  It  will  often  be 
advantageous  to  have  a  settling  tank  connected  with  those 
of  the  first  class,  to  prolong  the  safe  use  of  the  filter  as 
long  as  possible ;  while  the  same  object  is  gained  in  some 
of  the  second  class  by  bringing  the  water  in  at  the  bottom, 
in  which  case  there  should  be  a  space  below  the  filtering 


206 


WATER. 


mcdiiina  to  allow  the  suspended  matters  to  fall  away  from 
the  latter.  Tliose  intended  to  filter  the  whole  supply  of 
the  house  are  generally  cleansed  by  reversing  the  current 
and  washiuir  the  collected  dirt  out  of  the  filter  into  a  drain 


Fig.  47. 


Pasteur  filter  with  ro.sLTVoir  for  fillLTcd  wuter. 

or  sewer,  the  first  water  ])assing  through  the  filter  after 
this  is  done  being  also  discarded.  In  such  filters  the 
quantity  of  filtering  material  should  be  sufficient  to  purify 


USE  OF  COAGULANTS.  207 

thoroughly  the  water  passing  through  it,  and  yet  shoakl 
not  be  SI)  heavy  that  the  reverse  or  washing  current  can- 
not lift  it  and  separate  the  particles  so  that  by  their  scour- 
ing action  upon  one  another  they  may  be  cleansed  and  all 
the  dirt  washed  out.  These  filters,  also,  may  be  so  ar- 
ranged that  a  small  quantity  of  a  coagulant,  like  alum,  is 
automatically  added  to  the  water  before  filtration.  If  this 
be  done,  care  must  be  had  to  supply  no  more  of  the  coagu- 
lant than  suitable  tests  show  to  be  necessary,  else  the 
excess  may  be  carried  through  the  filter  in  solution. 

Several  filters  of  the  second  class  have  been  provided 
with  self-cleansing  devices  to  obviate  opening  or  taking' 
the  filter  apart  as  frequently  as  would  otherwise  be 
necessary.  Of  these  one  of  the  very  best  is  that  of  the 
Columbia  filter,  which  has  a  porous  tube  (or  tubes)  very 
similar  to  those  of  the  Pasteur-Cham  berland  type. 
Around  this  tube  is  a  mass  of  white  quartz  sand,  which 
is  set  in  active  motion  by  the  opening  of  the  cleansing 
valve  and  thoroughly  scours  the  exterior  of  the  filtering 
tube  until  the  latter  is  entirely  cleansed  of  the  suspended 
matter  which  it  has  removed  from  the  water.  Moreover, 
as  the  water  is  received  into  an  air-tight  reservoir  and 
accumulates  there,  wdien  not  immediately  used,  until  the 
air-pressure  in  the  reservoir  equals  the  pressure  in  the 
street-main,  the  opening  of  the  cleansing  valve  permits  the 
compressed  air  to  drive  the  filtered  water  back  through  the 
filtering  tube  and  thus  to  cleanse  its  pores  of  any  impuri- 
ties that  may  have  entered  them.  A  few  moments  each 
day  and  the  turning  of  a  valve  suffice  for  the  cleansing, 
and  so  effectual  is  it  that  most  of  the  objections  to  tube- 
filters  are  eliminated.  In  fact,  while  giving  a  germ-free 
water,  more  is  obtainable  per  day  per  tube  with  this  filter, 
and  there  is  less  annoyance,  loss  of  time,  and  risk  of 
breakage  of  tubes  in  the  cleansing. 


208  WATER. 

No  matter  what  kind  of  filter  is  used,  the  drinking- 
water  should  always  be  boiled  in  times  of  epidemics  or 
when  the  water  before  filtration  is  especially  impure ;  for, 
though  the  Berkfeldt,  the  Pasteur-Chamberland,  and  a  few 
other  filters  are  practically  bacteria-proof,  there  always  re- 
mains a  possibility  that  disease  germs  may  by  some  means 
pass  through  the  filtering  medium  or  gain  access  to  the 
water  after  it  is  filtered.  The  writer's  own  opinion  is  that 
there  is  a  saprophytic  or  biologic  action  in  most  good  filters 
that  are  regularly  and  frequently  cleaned  very  similar  to 
that  which  takes  place  in  filter-beds  on  a  large  scale,  and 
that  ordinarily  few,  if  any,  bacteria  pass  through  with  the 
water ;  but,  nevertheless,  the  risk  should  not  be  taken  if 
there  is  danger  of  incurring  disease  at  any  time. 

Filters  in  which  the  material  is  cemented  up  so  that  it 
cannot  be  removed  for  cleaning  or  renewal  should  not  be 
used.  Sponge,  wool,  etc.,  are  liable  to  decompose  and 
give  organic  matter  to  the  water  and,  moreover,  cannot  be 
thoroughly  cleaned.  Asbestos  acts  only  as  a  mechanical 
filter  and  may  allow  albuminous  matter  and  disease  germs 
to  pass.  Asbestos-cloth  may  be  used,  however,  to  support 
the  other  filtering  media  in  those  filters  where  the  water- 
supply  enters  at  the  bottom,  and  it  has  the  advantage  that 
it  can  be  perfectly  sterilized  by  fire.  Small  tap  filters  are 
insufficient  for  the  work  required  of  them  and  soon  clog. 
Pocket  filters  are  simply  strainers,  and  have  little  oxi- 
dizing power.  They  may  be  quite  useful  for  tourists, 
hunters,  etc.,  but  sliould  l)o  frequently  sterilized  l)y  boil- 
ing. Ordinarily,  filters  should  not  be  placed  in  rain-water 
cisterns,  but  outside,  where  they  may  be  readily  cleaned. 

Among  the  best  filtering  media  are  sand,  animal  char- 
coal, magnetic  carbide  of  iron,  spongy  iron,  etc.  Unglazcd 
porcelain  or  bisque,  as  is  used  in  the  Pasteur-Chamberland 


MATERIALS   USED  AS  FILTERING  MEDIA.      209 

filter,  is  an  excellent  medium,  and  is  practically  germ- 
proof,  though  some  observers  state  that  bacteria  will  pass 

Fig.  48. 


Glass  model  of  Loomis-Manning  filter,  showing  filter  in  action. 


through  uncleancd  filters  of  this  material  after  five  or  six 
days  of  use.     Others  claim  that  these  are  not  bacteria,  but 

14 


210 


WATER. 


only  the  mycelia  of  certain  budding  fungi,  with  no  power  of 

reproduction,  and  the  former  statement  seems  to  have  been 


Fig.  49. 


Glass  model  of  Loomis-MaiiniiiK  filter,  showing  sclf-bcouring  of  material 
during  cleansing. 

positively  disproved  with  respect  to  the  germs  of  ty])hoid 
fever,  colon  bacilli,  and  similar  organisms.     The  tubes  of 


MATERIALS  USED  AS  FILTERING  MEDIA.      211 

the  Berkfeldt  filter  were  formerly  made  of  diatoraaceous 
earth,  moulded  into  shape  by  powerful  hydraulic  pressure, 
so  that  the  water  percolated  through  the  pores  of  the 
minute  fossil  shells  rather  than  between  them.  If  kept 
clean,  these  give  good  service,  but  it  has  been  recently 
stated  that  typhoid  bacilli  will  pass  through  them  after 
several  days.  Stone  filters  may  be  good,  and  resemble 
the  porcelain  ones  in  action,  but  are  apt  to  be  slow  and 
must  be  cleaned  often.  Sharp,  clean  sand,  not  too  fine, 
has  fair  filtering  properties,  as  it  arrests  most  of  the  sus- 
pended matters  and  bacteria,  beside  oxidizing  somewhat 
the  dissolved  organic  matters.  It  makes  a  good  first  layer 
for  a  filter,  because  it  is  cheap  and  can  be  easily  renewed 
or  else  readily  cleansed  and  sterilized  by  boiling.  Crushed 
quartz  is  of  practically  the  same  nature. 

Animal  charcoal  is,  when  fresh,  an  excellent  material, 
as  it  removes  both  suspended  and  dissolved  matters, 
organic  and  inorganic,  and  even  color.  It  acts  both 
mechanically  and  chemically,  and  with  a  good  volume  of 
it,  water  may  pass  through  rapidly  and  be  well  purified. 
But  after  a  time  it  ceases  to  be  eifective,  nor  must  water 
be  left  too  long  in  contact  with  it,  as  it  will  give  up 
organic  matter  to  the  water  again  and  also  calcium  phos- 
phate, the  latter  especially  favoring  the  development  of 
micro-organisms.  Moreover,  fresh  organic  matter,  and 
possibly  bacteria,  are  said  to  pass  through  it  readily, 
though  dead  or  decomposing  matter  is  retained  and 
rapidly  destroyed.  It  should  be  changed  or  cleansed, 
even  when  in  sufficient  bulk,  three  or  four  times  a 
year ;  oftener  if  the  water  to  be  filtered  is  very  impure. 
It  is  more  efficacious  than  any  other  substance  in  remov- 
ing lead  from  water. 

Magnetic  carbide  of  iron   is  one  of  the  best  filtering 


212  WATER. 

materials,  as  it  has  considerable  power  in  oxidizing  or- 
ganic matters,  converting  them  into  nitrates  and  nitrites, 
the  action  being  greater  the  longer  the  water  is  in  contact 
with  it.  It  acts  partly  by  surface  condensation  of  oxy- 
gen ;  partly,  perhaps,  by  electrolytic  action.  If  sand  be 
used  as  a  first  layer  to  remove  solid  matters  so  that  the 
water  reaches  the  carbide  perfectly  clear,  and  if  the  sand 
be  frequently  renewed  or  cleansed,  the  carbide  need  never 
be  changed ;  but  the  filtration  must  be  intermittent  so 
that  the  carbide  may  be  frequently  aerated.  Spongy  iron 
has  an  action  very  similar  to  that  of  the  magnetic  carbide 
on  organic  matters,  and,  like  it,  the  action  is  the  greater 
the  longer  the  contact.  It  must  be  kept  covered  with 
water  to  prevent  rusting  and  caking,  and  should  be  re- 
newed about  once  a  year.  The  small  amount  of  iron 
that  the  magnetic  carbide  and  spongy  iron  give  to  the 
water  may  be  removed  by  passing  it  through  a  layer  of 
pyrolusite — a  crude  magnesium  oxide.  A  mixture  of 
jjyrolusite  and  sand  or  crushed  quartz  makes  an  excellent 
filtering  material. 

Ice  should  not  be  added  to  filtered  or  drinking-water, 
as  freezing,  even  fi)r  a  long  time,  may  not  kill  certain 
disease  germs.  Prudden  has  kept  typhoid  bacilli  frozen 
iii  ice  for  more  than  three  months  without  destroying  their 
power  of  growth  and  reproduction  when  brought  to  a 
suitable  temperature.  The  same  objections  do  not,  of 
course,  pertain  to  artificial  ice  carefully  made  from  dis- 
tilled water  as  to  that  from  polluted  ponds  or  rivers ;  but 
it  is  well  to  cool  the  water  by  placing  it  in  stoppered 
bottles  upon  ice  or  in  vessels  surrounded  by  ice  rather 
than  by  adding  the  ice  to  the  water  directly. 

The  inadvisability  of  using  ice-water  freely  as  a  bev- 
erage should   be  mentioned   here,  as  the  habit  is  almost 


EXAMINATION  OF  DRINKING-WATER.  213 

certain  to  cause  much  harm  to  the  digestive  apparatus, 
and  to  give  origin  not  only  to  intractable  dyspepsias,  but 
to  troubles  even  more  serious.  If  used  at  all,  ice-water 
should  be  taken  slowly  and  in  small  quantities,  and  as 
little  as  possible  should  be  imbibed  at  meal-time,  in  order 
to  prevent  chilling  of  the  stomach  and  consequent  check- 
ing of  the  digestion.  Its  use  and  the  liking  for  it  are 
mainly  a  matter  of  habit  which  it  is  hygienic  wisdom  to 
overcome. 

The  Examination  of  a  Drinking-water  should  have 
regard  to  its  physical,  bacterial,  and  chemical  properties 
as  well  as  to  a  consideration  of  all  the  conditions  affecting 
its  source,  storage,  and  distribution.  Consequently,  a 
decision  on  the  purity  of  water  should  be  governed  by 
all  the  available  knowledge  of  the  circumstances  :  whether 
it  is  well-water,  spring-water,  rain-water,  or  river-water ; 
whether  it  has  been  at  any  time  exposed  to  pollution ;  in 
what  kind  of  a  cistern  or  reservoir  it  has  been  stored,  etc. 

A  physical  examination  of  water  considers  the  color, 
clearness,  sediment,  lustre,  taste,  and  smell.  Pure  water 
has  a  bluish  tint,  but  most  waters  are  grayish,  greenish, 
yellow,  or  brown.  Yellow  or  brown  waters  are  subject  to 
suspicion,  as  the  color  may  be  due  to  animal  matter  or  sew- 
age, though  vegetable  matters  or  iron  may  give  the  same 
color.  Green  waters  are  usually  harmless,  the  color  being 
due  to  vegetable  matters.  The  color  is  judged  by  allow- 
ing the  sediment  to  settle  and  then  siphoning  or  pouring 
off  the  supernatant  water  into  a  tall  glass  vessel  or  tube 
to  the  depth  of  about  twenty-four  inches ;  the  color  is 
then  compared  with  that  of  a  similar  dejjth  of  distilled 
water,  looking  down  through  both  upon  a  white  surface. 

The  clearness  of  a  Avater  is  to  he  estimated  in  the  same 
way,  except  that  the  sediment  is  to   be  shaken  up  with 


214  WATER. 

the  water.  The  depth  needed  to  obscure  print  of  a  cer- 
tain size  and  kind  of  type  may  be  used  as  an  index. 
Where  the  solid  matter  will  not  readily  settle,  owing  to 
the  minuteness  and  lightness  of  the  particles,  one  should 
determine  w^hether  the  use  of  a  coagulant  and  filtration  is 
indicated,  or  whether  boiling  will  tend  to  precipitate  the 
sediment.  The  sediment  may  be  roughly  judged  by  the 
eye  as  to  whether  it  is  mineral  or  otherwise  ;  it  should  also 
be  examined  microscopically,  for  which  purpose  it  may  be 
collected  by  using  a  centrifugal  apparatus  or  by  allowing 
it  to  settle  from  the  water  in  a  conical  glass  and  then 
removing  it  to  the  slide  with  a  pipette.  Mineral  matters 
are  recognized  ])y  their  crystalline  or  amorphous  structure 
or  by  micro-chemical  tests;  vegetable  cells,  portions  of 
leaves,  etc.,  by  their  structure  and  the  presence  of  chlo- 
rophyll ;  animal  substances,  as  hair,  wool,  epithelial  and 
other  cells,  by  their  peculiar  characteristics.  Dai'k-brown, 
globular  masses  may  come  from  sewage.  Anything  indi- 
cating that  water  has  come  from  human  habitation  renders 
it  suspicious,  as  it  may  therefore  contain  sewage  or  other 
polluting  substances.  Some  of  the  larger  animalculse  and 
sometimes  iron  may  be  detected  witli  the  naked  eye.^ 

The  lustre  is  supj)()sed  to  indicate  the  amount  of  aera- 
tion ;  it  may  ])e  nil,  dull,  vitreous,  or  adamantine.  It 
should  not  be  forgotten  that  a  very  impure  water  may  be 
clear,  briglit,  and  sparkling. 

Any  water  of  peculiar  or  unpleasant  taste  should  be 
considered  with  suspicion.  Dissolved  animal  matters 
may  be  tasteless,  but  suspended  substances  give  a  peculiar 
taste,  whether  animal  or  vegetal.  Iron  is  about  the  only 
ordinary  mineral  that  can  be  tasted  in  small  quantities. 

1  S(!(r  J.  C.  MacDonald's  Guide  to  Microscopic  Examiuation  of  Drink- 
ing-water. 


THE  EXAMINATION  OF  POTABLE   WATER.      215 

Good  Avater  depends  for  its  taste  mainly  upon  its  gases, 
and  water  free  from  gas  tastes  flat. 

The  smell  of  a  water,  if  it  has  any,  may  be  brought  out 
by  heating  gently  to  about  110°  F,,  or  by  boiling  it.  This 
may  make  evident  a  fecal  odor,  although  hydrogen  sul- 
phide may  mask  this  latter ;  in  such  a  case  the  sulphide 
may  be  removed  by  adding  a  little  cupric  sulphate  to  the 
water.  The  odor,  may  also  be  developed  by  alloM'ing  the 
water  to  stand  in  a  stoppered  bottle  in  a  warm  place  for 
a  few  days. 

A  bacteriological  analysis  is  almost  as  necessary  as 
a  chemical  one,  for  purity  in  the  one  respect  does  not 
necessarily  indicate  purity  in  the  other.  The  presence  of 
Bacterium  coll  communis  in  a  water,  irrespective  of  any 
pathogenic  organisms,  would  create  more  than  a  suspicion 
of  contamination  by  fecal  matter,  as  this  microbe  is  prac- 
tically a  constant  occupant  of  the  human  intestinal  tract. 
But  water  may  be  capable  of  carrying  typhoid  or  other 
infection  and  yet  be  free  from  colon  bacilli,  since  the 
disease  germs  may  have  been  introduced  into  the  water 
from  urine  rather  tlian  feces. 

Water  may  be  collected  for  bacteriological  analysis  in 
sterilized,  closed  bulbs  blown  from  glass  tubing.  The 
heat  used  in  sealing  the  ends  creates  a  partial  vacuum 
within  the  bulb,  so  that  if  the  tip  of  one  end  be  broken 
off  beneath  the  surface  of  the  water,  the  latter  is  drawn 
into  the  bulb,  which  can  then  be  resealed  and  conveyed 
to  tlie  laboratory.  But  as  some  of  the  bacteria  may  mul- 
tiply rapidly  in  transportation  and  as  some  species  may 
even  destroy  others,  it  is  always  best,  if  possible,  to  inocu- 
late the  tubes  of  sterilized  culture-media  at  the  place 
where  the  supply  for  examination  is  obtained.  Or  one 
may  add  a  small  quantity  of  the  water  to  melted  nutrient 


216 


WATER. 


gelatin  at  the  time  when  the  samples  are  taken  and  make 
plate  cultures  in  the  manner  already  described.  The 
number  of  colonies  resulting  therefrom  will  indicate  prac- 
tically the  number  of  bacteria  in  the  volume  of  water 
added  to  the  gelatin. 

Fig.  50. 


Poclcct-case  containinp;  sterilized  culture-tubes,  platinum  needle,  and 
alcohol  lamp,  used  for  obtaining  cultures  for  diagnosis,  etc. 


The  details  of  some  simple  but  fairly  accurate  tests  and 
methods  employed  in  the  chemical  analysis  of  drinking- 
water  will  be  given  in  another  chapter.  Here  we  need 
only  consider  the  influence  that  the  substances  sought  for 
in  the  analysis  have  in  affecting  potability,  and  within 
what    limits    Ave    may    consider   them    as    being   permis- 


COLLECTION  OF  WATER  FOR  ANALYSIS.       217 

sible  in  drinking-water.  The  water  should  be  filtered 
or  free  from  sediment  for  all  the  tests,  except  in  the 
estimation  of  nitrogen  as  ammonia  compounds  and  as 
organic  matter,  and  of  the  oxygen-consuming  power  of 
the  water. 

The  amount  of  total  solids  will  vary  with  the  source  of 
the  water,  and  much  more  may  be  present  in  some  cases 
without  risk  of  harm  than  would  be  safe  in  others ;  but 
usually  the  proportion  should  not  exceed  50  or  60  parts 
in  100,000.  Only  a  small  portion  should  be  volatile,  and 
there  should  be  little  charring  on  ignition,  except  in  the 
case  of  waters  from  peaty  soils ;  nor  should  there  be  any 
odor  on  ignition,  especially  of  ammonia  compounds,  as 
that  would  indicate  an  excess  of  animal  organic  matter. 
Deep  well-water  will  probably  have  much  more  total 
solids  than  rain-water  or  clear  river-water,  the  excess 
being  mainly  mineral  substances  dissolved  from  the  strata 
through  which  the  water  passes. 

Even  the  purest  waters  contain  a  little  chlorine,  usually 
in  the  form  of  sodium  chloride ;  but,  as  the  latter  is  a 
constant  constituent  of  household  slops  and  sewage  in 
general,  any  excess  of  chlorine  above  the  amount  common 
to  the  water  of  the  district,  unless  otherwise  accounted  for, 
will  be  decidedly  suspicions,  and  sewage  contamination 
should  be  looked  for.  So,  also,  any  sudden  increase  in 
the  proportion  of  chlorine  would  very  likely  indicate  the 
accession  of  some  new  source  of  contamination  to  the 
M'ater.  Unless  accounted  for  by  the  strata  traversed  or 
by  the  locality,  more  than  3  parts  of  chlorine  in  100,000 
of  water  is  very  suspicious. 

The  presence  of  considerable  "  free  ammonia  "  in  rain- 
water is  not  a  bad  sign,  as  it  has  probably  been  absorbed 
from  the  air ;  but  the  same  amount  in  subsoil- water,  espe- 


218  WATER. 

cially  if  with  an  excess  of  chlorine,  would  indicate  prob- 
able contamination  with  urine,  as  the  latter  rapidly 
undergoes  ammoniacal  putrefaction.  In  such  a  case  there 
will  probably  also  be  considerable  "albuminoid  ammonia," 
but  much  albuminoid  ammonia  with  little  free  ammonia 
and  chlorine  generally  indicates  vegetable  contamination. 
The  writer  is  acquainted  with  a  case  in  which,  although 
the  water  is  pure  and  from  an  unpolluted  source,  the 
albuminoid  ammonia  and  chlorine  are  in  marked  excess, 
the  former  being  altogether  of  vegetable  origin— ^from  a 
peaty  soil — and  the  latter  characteristic  of  the  whole  dis- 
trict, which  is  near  the  sea-coast.  The  free  ammonia  is, 
however,  slight  in  amount.  An  excess  of  free  ammonia, 
chlorine,  nitrates,  and  nitrites  indicates  animal  contamina- 
tion, though,  if  the  pollution  be  by  effluvia  alone,  there 
may  be  no  excess  of  chlorine.'  The  total  ammonia  in 
a  usable  w^ater  should  not  be  over  0.13  or  0.15  part  per 
1,000,000.  If  there  is  almost  no  "free"  ammonia,  the 
"albuminoid"  may  amount  to  0.10  part  per  1,000,000 
without  giving  cause  for  suspicion ;  likewise,  if  there  is 
but  little  "albuminoid,"  there  may  be  considerable  "  free  " 
ammonia ;  but  if  the  "  albuminoid "  exceeds  0.05  part 
per  1,000,000,  the  "free"  must  not  be  greater  than  this 
proportion.  The  simplest  test  for  ammonia  is  by  means 
of  Nessler's  reagent — a  solution  of  a  double  iodide  of 
potassium  and  mercury.  It  gives  a  yellow  or  yellowish- 
brown  coloration  when  anmionia  is  present. 

Organic^  matters  of  animal  origin,  and  therefore  nitro- 
genous, are  during  oxidation  partially  converted  into 
ammonium  compounds,  and  these,  by  the  action  of  cer- 
tain bacteria,  mav  be  further  oxidized  into  nitrites  and 
iiitrafes.     "  Nilrilication  takes  place  under  tlie  influence 

'  Kenwood's  Hyyioiiic  Lal>()i:itc)ry,  p.  4'.). 


VALUE  OF  RESULTS  OF  ANALYTICAL   TESTS     219 

of  microbes,  the  habitat  of  which  does  not  extend  more 
than  a  few  yards  below  the  surface  of  the  soil.  The 
nitrifying  action  is  probably  exerted  only  npon  the  am- 
monium which  is  formed  from  the  organic  matter.  The 
presence  of  some  substance  capable  of  neutralizing  acids 
is  necessary  to  continuous  action.  Calcium  and  magne- 
sium carbonates  fulfil  this  function.  Nitrates  are  the 
final  result  of  this  action ;  nitrites  are  present  at  any 
given  time  only  in  small  quantity."^  Deep  water  may, 
of  course,  also  contain  nitrates  taken  up  from  strata  rich 
in  these  salts. 

Although  nitrites  and  nitrates  are  not  harmful  in  the 
quantities  usually  found  in  water,  and  though  the  w^ater 
containing  them  may  have  been  thoroughly  purified  by 
natural  filtration  through  the  soil,  their  presence,  as  will 
be  seen  from  the  above  remarks,  is  important  in  deter- 
mining the  character  of  the  water.  The  presence  of  the 
slightest  trace  of  nitrites  is  always  suspicious,  and  any 
marked  amount  of  nitrates,  excepting  possibly  in  a  deep 
water,  should  require  close  investigation ;  the  nitrates  and 
nitrites  together  measured  in  terms  of  nitrogen  should  not 
exceed  1  part  per  1,000,000. 

The  hardness  should  not  be  greater  than  that  indicated 
by  20  or  30  parts  of  chalk  in  100,000,  and  the  more 
"  temporary  "  in  proportion  to  the  "  permanent "  hardness 
the  better. 

Phosphates,  not  from  phosphatic  strata,  help  to  indicate 
sewage  contamination.  So,  also,  do  sulphates,  thougli 
these  by  themselves  may  come  from  unimportant  sources. 

It  will  be  seen  from  the  above  statements  that  the 
opinion  regarding  any  water  must  be  based  on  a  broad 
consideration  of  all   the  circumstances  in  relation   to    it, 

1  Lcffinann  and  Bevan,  Examination  of  Water,  2d  edition,  p.  13. 


220 


WATER. 


and  iKjt  from  the  presence  or  absence  in  it  of  any  one 
or  two  sul)stauces  whicli  are  not  in  themselves  harmful. 
The  presence  of  poisonous  metals  above  the  limits  of 
safety,  however,  would  alone  contraindicate  the  use  of  a 
water.  For  instance,  there  should  not  be  more  than  0.04 
grain  of  lead  or  copper,  0.25  grain  of  zinc,  or  0.5  grain 
of  iron  to  the  gallon  in  any  water,  and  the  faintest  trace 
of  arsenic  condemns  it. 

The  following  table  has  been  adapted  from  Parkes : 
Classification  axd  Propekties  of  Various  Waters. 


Class. 


Physical. 


Microscopical. 


Chemical 
(parts  per  100,000). 


I. 

Pure 

water. 


II. 
Usable 
water. 


III. 

Suspicious 

water. 


IV. 

Dangerous 

water. 


Colorless  or  bluish 
tint:  transparent, 
sparkling,  and  well 
aerated ;  no  sediment 
visible :  no  smell : 
taste  palatable. 

Colorless  or  slight 
greenish  tint;  trans- 
parent, sparkling, 
and  well  aerated  ;  no 
suspended  matter, 
or  easily  separated 
by  coarse  fill  ration 
or  subsidence ;  no 
smell ;  taste  palata- 
ble. 

Yellow  or  strong 
green  color ;  turbid  ; 
con-lderable  s  u  s- 
pended  matter;  uo 
smell,  but  any 
marked  taste. 


Yellow  or  brown 
color:  turbid,  and 
not  easily  purified 
by  coarse  filtration; 
large  amount  of  sus- 
pended matter;  any 
marked  smell  or 
taste. 


Mineral  matter; 
vegetable  endo- 
chrome ;  large  ani- 
mal forms ;  no  or- 
ganic debris.  i 


Same  as  for  pure 
water. 


Vegetable  and  ani- 
mal forms,  more  or 
less  pale  or  color- 
less ;  organic  ilebris : 
fibres  of  clothing  or 
other  house  refuse. 


Bacteria  of  any 
kind  ;  fungi ;  numer- 
ous vegetable  or  ani- 
mal forms  of  low 
types;  epithelia  or 
other  animal  struct- 
ures; evidence  of 
sewage  or  ova  of 
parasites,  etc. 


Chlorine  under         1.4 
Total  solids  under    7.14 
Ammonia  under      0.007 
Nitrogen,  as  nitrites  &  ni- 
trates, &  in  albuminoid 
ammonia,  under  0.0'2:j 
Total  hardness         8.05 
Chlorine  under        4.3 
Total  solids   "         42.8 
Ammonia      "  0.015 

Nitrogen,  as  nitrites 
&  nitrates,  and  in 
albuminoid  am- 
monia, under        0.125 
Total  hardness       17.03 


Chlorine  4  to  7 

Total  solids   A^  to  71 
Ammonia    0.015  to  0.023 
Nitrogen,  as  nitrites 

<t  nitrates 

0.124  to  0.237 
Total  hardness 

above  17.0 

Chlorine  above         7.14 
Total  solids"  71.4 

Ammonia    "  0.0225 

Nitrogen,  as  nitrites 

&.  nitrates,  above  0.242 
Total  liardness 

above  28.05 


CHAPTEK  VI. 

FOOD. 

The  use  of  food  is  necessary  to  build  up  the  body- 
structure,  to  repair  waste,  and  to  furnish  force  and 
energy  for  the  proper  action  of  all  the  organs,  tissues, 
and  parts  of  the  body.  In  addition,  certain  substances 
are  needed,  not  so  much  because  they  become  a  part  of 
the  tissue  framework  or  yield  kinetic  energy  directly,  as 
that  they  are  essential  factors  in  the  multitudiuous  chemi- 
cal reactions  and  changes  that  are  continually  occurring 
withiu  the  living  person.  We  may,  accordingly,  define 
a  food  as  anything  that  tends  to  fulfil  any  one  of  these 
functions,  provided  it  is  not  at  the  same  time  by  nature 
harmful  to  the  economy,  and  that  it  does  not  produce 
physiological  effects  out  of  proportion  to  its  nutritive  or 
metabolic  activities. 

Strictly  speaking,  this  definition  might  include  air  and 
water,  as  the  former  is  necessary  to  supply  oxygen  for 
union  with  other  foods  or  with  the  tissues  themselves, 
and  the  latter  is  needed  to  assist  in  the  solution  and 
assimilation  of  food-stuffs,  to  maintain  the  fluidity  of  the 
body-juices  and  to  moisten  the  tissues  effectively,  to  pre- 
serve roundness  of  form,  and  to  flush  out  and  remove 
from  the  system  those  waste  matters  and  excrementitious 
substances  whose  retention  gives  rise  to  the  symptoms  of 
certain  autogenetic  diseases.  But  they  are  not  usually 
included  in  the  category  of  foods,  and,  having  already 
been  considered,  they  may  be  passed  over  in  this  connec- 
tion with  but  incidental  reference  here  and  there. 

221 


222  FOOD. 

If  we  classify  foods  according  to  their  chemical  compo- 
sition, we  may  separate  them  into  the  following  main 
divisions:  1.  Proteids  and  albuminoids;  2.  Carbohy- 
drates ;  3.  Hydrocarbons  or  fats ;  and  4.  Salts,  extrac- 
tives, etc.  Each  group  is  subject  to  diiferent  digestive 
and  metabolic  processes,  and  each  has  usually  a  different 
office  within  the  body ;  for  experience  and  careful  experi- 
ments both  show  that  all  of  these  different  food-principles 
are  needed  to  sustain  life  and  maintain  health  for  any  con- 
siderable length  of  time,  and  that,  having  them,  nothing 
else  except  air  and  water  is  absolutely  necessary  ;  although 
what  are  sometimes  called  the  accessory  food-stuffs  and 
many  pleasant  volatile  odors  and  flavors  are  desirable 
and  advisable  adjuncts  to  the  food  proper,  since  they 
greatly  favor  its  reception,  digestion,  and  assimilation. 
But,  though  each  class  of  food  has  its  own  special  function 
in  the  economy  of  nutrition,  in  times  of  need  or  depriva- 
tion any  one  of  the  first  three  divisions  may,  in  a  way, 
supply  the  place  of  either  of  the  other  two. 

FothergilP  epitomizes  the  use  of  the  food-principles 
in  this  way  :  "  The  carbohydrates  are  the  body-fuel,  the 
surplusage  being  stored  as  fat ;  the  albuminoids  (proteids) 
serve  to  repair  the  tissues  as  they  wear  out ;  the  salts 
form  the  blood-salts ;  the  fat  helps  to  build  up  normal 
health  tissues,  the  excess  being  burnt  as  body-fuel.  That 
is  the  real  object  of  food." 

Wliile  in  the  main  correct,  this  is  a  broad  statement 
of  facts,  and  it  needs  qualification.  For  instance,  just 
as  there  is  some  wear  and  tear  in  any  mechanical  ma- 
chine while  in  use,  which  must  eventually  be  provided 
for;  so  in  the  human  body  with  its  manifold  activities 
there  must  be  some  destructive  effect  upon  the  body- 
'  Manual  of  Dietetics,  p.  5. 


FOOD-PRINCIPLES.  223 

structure  and  tissue  framework,  and  it  is  to  renew  and  re- 
place this  inevitable  loss  of  material  that  a  part — perhaps 
the  larger  or  greater  part — of  the  proteid  food  is  taken. 
But  we  also  know  that  in  addition  to  this  simple  re- 
pair and  replacement  of  tissue,  "  the  presence  of  nitrogen- 
ized  structure,  and  its  participation  in  the  action  going  on 
there,  is  a  necessary  condition  for  the  manifestation  of 
any  vital  energy  or  any  chemical  change,"  and  we  have 
reason  to  believe  that,  entirely  apart  from  the  idea  of 
repair,  proteid  food  is  essential  to  the  development  and 
maintenance  of  this  chemical  and  vital  activity  of  nitro- 
genized  tissue. 

Confirming  this,  Pettenkofer  and  Voigt  have  shown 
that  the  absorption  of  oxygen  is  largely  determined  by 
the  nitrogenous  substances  composing  the  tissues  of  the 
body,  and  that  it  is  proportional  to  their  size  and  vigor. 
Moreover,  it  is  known  that  proteids  may  be,  in  part, 
converted  into  fat  and  possibly  into  other  oxidizable  sub- 
stances, and  thus  become  a  source  of  body-heat  and 
energy. 

So,  also,  with  the  fats  and  carbohydrates.  While  they 
are  not  immediately  nor  entirely  interconvertible,  and 
while  neither  class  may  be  permanently  excluded  from 
the  diet,  yet  in  emergency  either  may  apparently  fully 
supplant  and  substitute  the  other  for  a  time,  and  we  can- 
not yet  say  exactly  how  similar  or  dissimilar  their  service 
within  the  body  is. 

However,  while  Fothergill's  epitome  needs  this  emen- 
dation, known  facts  make  it  comparatively  easy  to  gain 
a  fair  idea  of  the  differences  and  functions  of  the  proxi- 
mate food-principles,  to  which  end  some  help  will  proba- 
bly be  given  by  the  following  table  -} 

1  Notter  and  Firth,  Treatise  on  Hygiene,  p.  257. 


224 


FOOD. 


Pkoperties  and  Functions  of  Food-principles. 


Examples. 


Functions. 


NiTEOGESODS  SUBSTASCES. 

1.  Proteids. 

All  substances  containing  nitro- 
gen of  a  composition  identical  with, 
or  nearly  that  of  albumin  ;  propor- 
tion of  5r  to  C  being  nearly  as  2  to  j 
7  or  4  to  14. 


1(a).  Substances  containing  a 
larger  proportion  of  nitrogen  are 
apparently  less  nutritious. 

Proportion  of  N  to  C  about  2  to 
5"^  or  4  to  11. 

\(b).  Extractive  matters,  such  as 
are  contained  in  the  juice  of  the 
flesh. 


NON-NITKOGENOUS  SUBSTANCES. 

2.  Fats  (or  Hydrocarhons). 

Substances  containing  no  nitro- 
gen, but  made  up  of  carbon,  hydro- 
gen, and  oxygen;  the  proportion 
of  oxygen  being  less  than  sufficient 
to  convert  all  the  hydrogen  into 
water. 

Proportion  of  unoxidized  H  to  C, 
about  1  to  7. 

3.  Carbohydrates. 

Substances  containing  no  nitro- 
gen, but  made  up  of  carbon,  hy- 
drogen, and  oxygen ;  the  oxygen 
being  exactly  sufficient  to  convert 
all  the  hydrogen  into  water. 

Propoii^ion  of  water  to  carbon, 
about  3  to  2. 

.3(a).  Vegetable  acids  (and  peclous 
substances). 

Substances  containing  no  nitro- 
gen, but  made  up  of  carbon,  hy- 
drogen, and  oxygen  ;  the  o.xygen 
being  generally  in  greater  amount 
than  is  sufficient  to  convert  all  the 
hydrogen  into  water. 


4.  Salts  {mineral). 


Animal : 
Albutuin, 
Fibrin, 
Syntonin, 
Myosin, 
Globulin, 
Casein. 

Vegetable : 
Glutin, 
Legumin. 

Gelatin, 
Ossein, 
Chondrin, 
Keratin, 


Olein, 

Stearin, 

Margarin, 


Starch, 
Dextrin, 
Cane-sugar, 
Grape-  " 
Lactin    (or 
milk-sugar) 

(MoreOthan 
is  sufficient 
to    convert 
all  H   into 
HoO.) 
Oxalic  acid. 
Tartaric  " 
Citric        " 
Malic 
(No     excess 

of  O.) 
Acetic  acid. 
Lactic     " 

Sodium 

chloride, 
Potassium 

chloride, 
Calcium 

phosphate, 
Magnesium 

phosphate, 
Iron,  etc. 


Formation  and  repair  of  tis- 
sues and  fluids  of  the  body. 

Kegulation  of  the  absorption 
and  utilization  of  oxygen.  May 
also  form  fat  and  yield  energy 
under  special  conditions.  In 
most  foods  the  above,  both  ani- 
mal and  vegetable,  are  largely 
converted  into  albumoses  and 
peptones. 

These  perform  the  above 
functions  less  perfectly,  or 
only  under  particular  circum- 
stances. 

These  substances  appear  es- 
sential as  regulators  of  digestion 
and  assimilation,  especially 
with  reference  to  the  gelatin 
group. 


Supply  of  fatty  tissues ;  nu- 
trition of  nervous  system  ;  sup- 
ply of  energy  and  animal  heat 
by  oxidation. 


Production  of  energy  and 
animal  heat  by  oxidation ; 
form  fats  and  possibly  some 
proteid. 


Preserve  the  alkalinity  of  the 
blood  by  their  conversion  into 
carbonates ;  furnish  a  small 
amount  of  energy  or  animal 
heat  by  oxidation. 


Various;  support  of  bony 
skeleton,  supply  of  HCl  for 
digestion,  etc.  Regulators  of 
energy  and  nutrition. 


PHYSIOLOGY  OF  DIGESTION.  225 

Dietetics  means  "  the  branch  of  medicine  or  hygiene 
that  treats  of  diet  and  dieting,"  and  its  study  inchides  '*'  a 
systematic  regulation  of  the  diet  for  hygienic  or  thera- 
peutic purposes."  It  considers  all  the  factors  that  affect 
the  proper  digestion  and  assimilation  of  food.  For  in- 
stance, it  is  not  alone  necessary  to  determine  just  what 
substances,  in  a  chemical  sense,  the  body  needs  to  sustain 
life  and  maintain  health.  Nor  is  it  sufficient  to  say 
that  a  man  must  have  just  so  much  of  this  and  so 
much  of  that  food,  for  there  must  always  be  a  varia- 
tion in  both  kind  and  quantity  to  meet  the  changing 
demands  of  the  system.  With  a  few  exceptions,  no 
matter  how  toothsome  or  healthful  a  certain  food  may 
be,  it  soon  palls  upon  the  appetite  if  necessity  compels 
its  continued  use  for  a  prolonged  period,  and  this  disgust 
may  be  so  impressed  upon  the  memory  of  the  sense  as 
to  cause  them  to  object  to  the  use  of  that  food  forever 
after. 

The  aesthetic  factors  in  the  preparation  and  serving  of 
food  must  also  be  taken  into  account,  and  the  success 
in  pleasing  the  taste  and  appetite  has  much  to  do  with  the 
progress  and  completeness  of  digestion.  Other  things 
being  equal,  palatable  and  agreeable  foods  are  disposed  of 
much  more  satisfactorily  than  others  not  so,  and  physi- 
cians and  others  should  learn  that  especially  in  sickness 
the  appearance  and  palatability  of  a  food  have  much  to 
do  with  its  acceptance,  not  only  by  the  patient,  but  by 
his  stomach  as  well.  Cleanliness  and  neatness  of  food, 
china,  and  napery  are  of  greater  value  than  expense  or 
show,  and  a  little  attention  and  tact  in  such  matters  will 
often  enable  a  patient  to  take,  enjoy,  and  retain  food  and 
receive  nourishment,  even  when  he  or  she  asserts  and 
believes  this  to  be  impossible. 
15 


226  FOOD. 

Another  factor  of  much  iin|)<)rtancG  in  the  digestion  of 
food,  but  one  too  often  too  lightly  considered,  is  the  mood 
or  state  of  mind  when  the  food  is  taken  and  while  it 
remains  in  the  alimentary  canal.  There  is  more  than 
moral  philosophy  in  maintaining  a  cheerful  and  a  tran- 
quil disposition  during  the  daily  meals  and  for  a  time 
thereafter;  while  there  are  numerous  instances  of  most 
serious  results  occurring  from  the  giving  way  to  anger  or 
other  intense  emotion  at  such  times,  the  digestive  func- 
tions being  either  completely  checked,  or,  what  is  fre- 
quently worse,  so  altered  that  their  products  are  toxic  in 
character.  And  is  not  a  dyspeptic  often  so  because  of 
his  pessimism,  rather  than  a  misanthrope  because  of  his 
indigestion  ? 

Before  proceeding  further  it  will  be  well  to  consider 
briefly  the  physiology  of  digestion  in  so  far  as  it  concerns 
the  chemical  chano;es  occurrino;  in  the  food  while  it  is  in 
the  digestive  tract.  These  changes  are  brought  about  by 
tlie  action  of  certain  bodies  secreted  or  elaborated  by  the 
digestive  organs  and  glands,  which  we  have  been  in  the 
habit  of  calling  unorganized  ferments,  but  which  would, 
perhaps,  better  be  known  hereafter  as  enzymes.  Unorgan- 
ized ferments  are  so  called  because  they  have  not  the  defi- 
nite cell-formation,  life,  and  power  of  reproduction  which 
belong  to  the  yeasts,  mould-fungi,  and  bacteria  which  bring 
about  the  fermentative  changes  in  organic  substances  so 
commonly  within  the  knowledge  of  everyone,  such  as  the 
conversion  of  saccharine  solutions  into  alcohol,  of  alcohol 
into  acetic  acid,  etc. 

But  though  unorganized,  the  enzymes  likewise  act  upon 
organic  matter;  for  example,  upon  the  food  which  we  eat, 
and — like  the  other  ferments — they  ap])arently  do  this 
simply  l)y   their  presence   rather  than   by   entering   into 


PHYSIOLOGY  OF  DIGESTION.  227 

actual  combination  with  the  matter  acted  upon,  as  do  ordi- 
nary chemical  reagents.  They  are  undoubtedly  the  prod- 
ucts of  glandular  protoplasm,  probably  proteid  in  nature, 
and  some,  at  least,  very  likely  belonging  to  the  group  of 
nucleo-albumins,  which  latter  form  a  component  part  of 
every  organic  cell. 

The  comprehension  of  the  digestive  functions  will  be 
greatly  simplified  if  the  student  remembers  that  "  with  the 
possible  exception  of  the  coagulating  enzymes,  the  action 
of  the  enzymes  is  that  of  hydrating  agents  :  they  produce 
their  effect  by  what  is  known  as  hydrolysis — that  is,  they 
cause  the  molecules  of  the  substance  upon  which  they  act 
to  take  up  one  or  more  molecules  of  water ;  the  resulting 
molecule  then  splits  or  is  dissociated,  with  the  formation 
of  two  or  more  simpler  bodies."  ^ 

Thus  the  insoluble  proteids  and  carbohydrates  become 
respectively  the  soluble  peptones  and  sugars  of  their  allies, 
capable  of  being  absorbed  into  the  myriad  capillaries  that 
are  distributed  throughout  the  lining  membrane  of  the  ali- 
mentary tract;  and  even  the  change  that  takes  place  in  fat 
when  digested  is  one  that  involves  the  taking  up  of  some 
water. 

There  are  four  characteristics  of  the  enzymes  worthy  of 
note  :  1.  That  they  are  all  soluble  in  water  and  glycerin, 
the  latter  being  specially  useful  in  making  stable  prepara- 
tions of  them  from  the  organs  producing  them.  2.  "  That 
very  low  temperatures  (0°  C.)  retard  or  suspend  entirely 
their  action,  without,  however,  destroying  the  enzyme ; 
that  for  each  enzyme  there  is  a  temperature  at  which  its 
action  is  greater,"  and  that  "  in  a  moist  condition  they 
are  all  destroyed  by  temperatures  below  the  boiling-point ; 
60°  to  80°  C.  are  the  limits  actually  observed." ^    3.  "  That 

1  American  Text-book  of  Physiology,  first  edition,  p.  219.  ^  Ibid. 


228  FOOD. 

tliey  never  completely  destroy  the  substance  upon  which 
they  act/'  probably  being  retarded  by  their  products  when 
the  latter  reach  a  certain  percentage.  "  When  these  are 
removed,  the  action  of  the  enzymes  begins  again."  4. 
"  Except  for  very  small  quantities,  it  may  be  said  that 
the  amount  of  change  caused  is  independent  of  the  amount 
of  enzyme  present  f  or,  rather,  "  with  increasing  amounts 
of  enzymes  the  extent  of  action  also  increases,  reaching  a 
maximum  with  a  certain  percentage  of  enzyme ;  increase 
of  enzyme  beyond  this  has  no  eifect."  The  amount  of 
work  capable  of  being  done  by  a  small  proportion  of  an 
enzyme  is  enormous,  good  pepsin,  for  instance,  having  the 
power  of  converting  2500  times  its  own  weight  of  proteid ; 
but  we  must  remember  that  this  power  is  not  infinite,  and 
that  after  a  time  the  enzymes  will  cease  to  act. 

There  are  five  groups  or  classes  of  enzymes  concerned 
with  the  proper  digestion  of  food  to  be  found  in  the  ani- 
mal body,  and  it  is  interesting  to  note  that  examples  of 
each  of  these  classes  are  also  to  be  found  in  various  mem- 
bers of  the  vegetable  world.  The  two  principal  remaining 
classes,  l)eing  neither  of  animal  origin  nor  digestive  agents, 
need  onlv  be  mentioned  here  :  they  are  the  glucoside-split- 
tinfj  and  urea-spliffinf/  enzymes,  the  latter  being  produced 
by  certain  bacteria  and  converting  urea  into  ammonium 
carbonate. 

Considering  the  digestive  processes  in  their  order  as  the 
food  proceeds  from  the  mouth  through  the  alimentary 
canal,  we  find  that  the  first  active  secretion  or  fluid  is  the 
saliva,  and  that  its  enzyme  is  jAyalin,  belonging  to  that 
group  which  converts  the  insoluble  carbohydrates  (starches) 
into  soluble  sugars,  maltose,  etc.  Ptyalin  acts  best  in 
neutral  or  slightly  alkaline  media,  at  about  the  body-tem- 
perature (40°  C),  and  u])nn  cooked  niueh  lu'tter  than  upon 


CHAEACTEPdSTICS   OF  DOMESTIC  ENZYMES.      229 

raw  starch.^  Its  action  is  retarded  or  totally  cheeked  by 
a  low  temperature  or  by  strongly  alkaline  or  moderately 
acid  solutions,  and  the  enzyme  itself  is  probably  destroyed 
by  an  increase  in  acidity  equal  to  that  of  the  gastric  juice, 
or  by  a  temperature  of  65°  or  70°  C.  The  reason  it  con- 
verts cooked  starch  so  much  more  quickly  is  probably  be- 
cause the  heating  process  breaks  up  the  cellulose  envelopes 
upon  which  the  ptyalin  has  almost  no  effect  and  which 
protect  the  starch  granules  within  from  its  action.  The 
heat  also  causes  a  very  close  union  between  the  molecules 
of  starch  and  water,  this  facilitating  the  later  hydrolysis 
by  the  enzyme. 

In  addition  to  its  digestive  function,  the  saliva  also 
serves  to  moisten  dry  food  so  that  it  may  be  swallowed, 
and  to  dissolve  sapid  and  savory  substances  that  they  may 
be  duly  appreciated  by  the  organs  of  taste. 

Our  first  hvffienic  lesson  in  regard  to  the  disrestive 
functions  is,  therefore,  that  in  order  to  get  the  full  benefit 
of  the  salivary  secretions,  all  food,  and  especially  that  of 
a  starchy  nature,  should  be  well  masticated  and  retained 
in  the  mouth  for  some  little  time,  instead  of  its  being 
"  bolted "  at  once  or  after  a  hasty  bite  or  two.  Xor 
should  very  cold  or  very  hot  beverages  be  taken  at  the 
same  time  ^dth  the  food,  for  not  only  will  the  action  of 
the  ptyalin  be  thus  retarded  or  destroyed,  but  that  also, 
as  we  shall  see,  of  the  gastric  juice  within  the  stomach. 

'  Kubel  claims  to  have  found  that  an  alkaline  reaction,  even  -wheu 
very  weak,  actually  interferes  with  ptyalin  digestion,  but  that  it  is 
favored  by  a  weak  acid  reaction,  especially  if  the  acid  be  one  of  the 
stronger  ones,  like  HCl.  He  admits  that  an  amount  of  hydrochloric 
acid  equivalent  to  that  of  the  gastric  juice  checks  the  activity  of  the 
ptyalin,  but  believes  that  at  the  beginning  of  a  meal  and  for  a  time 
thereafter  salivary  digestion  takes  place  better  in  the  stomach  than  in 
the  mouth.     Boston  Medical  and  Surgical  Journal,  April,  1S99. 


230  FOOD. 

A  note  here  as  to  the  drinking  of  water  at  meal-time  will 
not  be  out  of  place.  A  moderate  quantity  of  proper  tem- 
perature will  probably  be  beneficial  rather  than  otherwise, 
since  it  helps  in  the  solution  of  the  food ;  but  an  exces- 
sive quantity  tends  to  harm  by  diluting  the  enzymes 
too  much,  thus  interfering  with  their  reactions,  and  by 
interfering  with  the  absorption  of  the  digested  matters. 

The  food,  having  passed  from  the  mouth  to  the  stom- 
ach, may  still  be  acted  upon  for  a  time  by  the  ptyalin 
until  the  work  of  the  latter  is  checked  by  the  acid  of  the 
gastric  juice.^  The  energy  of  digestive  action  is  then 
transferred  from  the  starches  to  the  proteid  constituents 
of  the  food,  the  chief  enzyme  now  being  jiepsin,  though 
we  also  iiud  in  the  gastric  juice  a  coagulating  ferment — 
rennin — which  acts  upon  soluble  proteids,  like  the  casein 
of  milk,  to  form  clots  or  curds. 

Pepsin  acts  only  in  an  acid  medium  (the  acidity  being 
supjjlied  normally  by  the  free  hydrochloric  acid  of  the 
gastric  juice),  and  best  at  the  body-temperature.  As 
stated,  extremes  of  temperature  are  adverse  to  its  activity 
and  may  check  it  altogether,  and,  likewise,  too  much  or 
too  little  acid  raay  have  the  same  eifect,  from  0.2  to  0.3 
per  cent,  of  HCl  being  the  normal  amount  and  giving  the 
best  results.     Rennin  ^  seems  in  the  normal  stomacli  to  act 

'  Recent  experiments  seem  to  show  that  "  ptyalin  digestion  normally 
continues  during  tiie  first  hour  of  gastric  digestiou,  or,  in  fact,  until  the 
hydrochloric  acid  secretion  reaches  the  normal  maximum."  A.  L. 
Benedict,  Journal  of  the  American  Medical  Association,  July  28,  1900. 
Grutzner  has  also  .«liown  (Pfliiger's  Archiv,  1905,  cvi.,  436)  that  the  reac- 
tion within  the  main  mass  of  the  food  in  the  stomach  may  remain  alka- 
line or  neutral  for  some  two  hours,  the  digestion  of  proteids  by  pepsin 
going  on  only  at  the  pyloric  end  and  in  that  part  of  the  food  that  was 
in  contact  with  the  stomach  walls. 

'■^  Oppenlieimcr  says  concerning  rennin:  "It  does  not  appear  to  have 
any  essential  significance  for  tln>  digestion  of  proteids.     II  is  strikingly 


GASTRIC  DIGESTION.  231 

only  on  the  casein  of  milk,  and  curdles  this  probably  be- 
cause it  is  then  more  easily  digested  by  the  pei)sin  and, 
later,  by  the  trypsin  of  the  pancreatic  juice. 

The  action  of  the  pepsin,  plus  the  acid,  upon  the  proteids 
of  the  food  is  a  hydrolytic  one,  and  the  end-products  are 
practically  hydrated  proteids,  called  albumoses  and  pep- 
tones— substances  especially  diifusible  and  capable  of 
absorption.  The  gastric  digestion,  therefore,  after  the 
action  of  the  ptyalin  has  been  checked  by  the  acid  gastric 
juice,  practically  has  to  do  only  with  the  albuminous  or 
nitrogenous  part  of  the  food,  the  remainder,  or  at  least 
that  part  of  it  not  yet  capable  of  absorption,  remaining 
unchanged  until  it  passes  further  on  into  the  intestines. 
Soluble  salts,  sugars,  and  part,  at  least,  of  the  peptones  as 
they  are  formed,  may,  however,  be  taken  up  by  the  stom- 
ach capillaries,  while  the  rest  of  the  food-mass,  kept  ever 
in  motion  by  the  muscular  movements  of  the  stomach- 
walls,  is  being  thoroughly  mixed  and  converted  by  the 
peptic  action  into  the  semi-liquid  substance  called  chyme, 
which  is  passed  at  intervals  and  in  small  quantities  through 
the  pyloric  opening  into  the  duodenum.  Long  before  the 
stomach  has  entirely  emptied  itself — which  may  only  be 
after  several  hours  of  activity ' — intestinal  digestion  is  well 
under  way,  and  in  some  respects  this  is  the  most  important 

absent  in  the  new-born,  who  consume  much  milk.  Zuntz  and  Sternberg 
have  even  found  that  milk  proteid  coagulated  by  rennin  is  less  easily- 
digested  than  the  original  milk  proteid,  and  attribute  to  this  in  part  the 
relatively  smaller  availability  of  milk  for  adults,  who  produce  more 
rennin."  (Torald  Sollmann,  The  Journal  of  The  American  Medical 
Association,  Feb.  9,  1907,  p.  521.) 

1  "Cannon  and  others  have  shown  that  the  main  mass  of  the  food 
remains  in  the  stomach  for  a  considerable  time — three  hours  with  a  car- 
bohydrate meal,  six  hours  with  a  proteid  meal,  twenty-one  hours  with 
a  fatty  meal.  A  portion  of  the  food  leaves  the  stomach  much  earlier." 
(Torald  Sollmanu,  loc.  cit.,  p.  522.) 


232  FOOD. 

as  well  as  the  most  comprehensive  process  of  all.  The 
three  secretions  to  whose  combined  action  the  chyme  is 
now  subject  are  the  pancreatic  juice,  the  bile,  and  the 
intestinal  juice.  All  are  alkaline  and  quickly  neutralize 
the  gastric  acid  ;  it  scarcely  need  be  noted,  then,  that  the 
remaining  enzymes  act  best  or  only  in  alkaline  media, 
though  one  of  them,  trypsin,  may  act  in  solutions  not  too 
strongly  acid. 

In  the  pancreatic  juice  we  find  three  enzymes,  practi- 
cally the  only  remaining  ones  of  much  importance ;  al- 
though in  the  rather  scanty  intestinal  juice  two  others 
have  been  found,  one  capable  of  converting  starch  into 
suo;ar,  and  the  other  of  invertins;  cane-sus:ar  into  levulose 
and  dextrose.  The  bile  contains  no  enzymes.  The  pan- 
creatic ferments  are  trypsin,  which  acts  upon  proteids 
and  albuminoids  even  more  powerfully  than  pepsin,  and 
likewise  converts  them  into  albumoses  and  peptones ; 
amylopsin,  which  is  practically  identical  with  ptyaliu  in  its 
function ;  and  steapsin,  which  causes  neutral  fats  to  take 
up  water  and  split  into  free  fatty  acids  and  glycerin. 

Under  the  action  of  the  trypsin  all  that  portion  of  the 
proteid  food  which  has  not  been  completely  digested  in 
the  stomach  reaches  that  stage  in  the  small  intestine  and 
is  absorbed  therefrom.  In  fact,  it  is  very  probable  that 
the  tryptic  digestion  is  often  the  more  important  of  the 
two.  As  the  action  of  the  saliva  upon  the  carbohydrates, 
which  form  the  greater  bulk  of  our  food,  must  of  neces- 
sity be  very  limited,  it  is  evident  that  almost  all  of  the 
starch  digestion  is  performed  by  the  amylopsin,  aided 
in  slight  measure  by  the  similar  enzyme  of  the  intestinal 
juice.  The  salts  and  other  soluble  elements  of  the  food 
have  already  been  absorbed,  and  there  remain  only  the 
fats  or  hydrocarbons. 


THE  PANCREATIC  ENZYMES.  233 

Under  the  influence  of  the  steapsin  a  comparatively 
small  portion  of  the  fat  in  the  food  is  separated  into 
glycerin  and  free  fatty  acids,  and  this  action  for  some 
reason  takes  place  much  more  rapidly  when  aided  by  the 
bile  than  with  the  pancreatic  juice  alone.  Then  these 
fatty  acids  unite  with  the  alkalies  and  alkaline  salts  of 
the  above  secretions,  but  especially  of  the  bile  and  intes- 
tinal juice,  to  form  soaps,  and  these  soaps  aid  in  emulsi- 
fying the  remainder  of  the  fats  and  in  thus  making  them 
ready  for  absorption,  which  latter  process  is  also  facili- 
tated by  the  direct  action  of  the  bile  upon  the  intestinal 
epithelium. 

The  student  must  not  get  the  idea  that  the  absorption 
of  digested  food  from  the  alimentary  canal  is  merely  a 
physical  process  and  a  matter  of  osmosis  or  diffusion. 
Accumulating  experience  indicates  that  it  is  in  a  meas- 
ure, if  not  largely,  vital  and  physiological,  and  that  "  the 
living  cells  of  the  intestinal  wall  appear  to  take  an  active 
share  in  the  process,  and  modify  the  action  of  the  physical 
factors  in  a  manner  not  at  present  understood."  This  is 
probably  especially  true  as  regards  the  absorption  of  the 
fats,  wdietlier  we  take  the  commonly  accepted  view  that 
most  of  the  fat  is  emulsified  and  only  a  small  portion  split 
up  and  saponified  in  the  intestine,  or  the  one  which  some 
have  advocated  of  late  years,  viz.,  that  almost,  if  not  all, 
of  the  fat  is  decomposed  and  dissociated,  and  compara- 
tively little,  if  any,  emulsified. 

The  digestive  processes  having  thus  been  outlined,  it 
will  be  well  to  learn  how  they  may  be  maintained  as 
complete  and  perfect  as  possible.  In  the  first  place,  the 
cooking  of  food  is  usually  an  essential  preliminary.  We 
cook  meats  not  only  to  make  them  more  agreeable  to 
the  palate,  but  also  to  facilitate  digestion.     The  effect  of 


234  FOOD. 

cooking  upon  muscle  (flesh)  is  "to  loosen  the  bundles  of 
fibrillse  from  each  other,  so  that  they  are  readily  torn 
asunder  or  crushed  by  the  teeth,"  while  the  various  con- 
nective tissues  are  softened  and  gelatinized,  not  only  thus 
becoming  more  digestible  and  nutritious,  but  also  allowing 
the  histologic  elements  which  they  bind  together  to  sepa- 
rate and  be  more  freely  acted  upon  by  the  solvent  fluids. 
So  with  the  vegetables,  the  heat  and  steam  soften  and 
rupture  the  cellulose  envelopes  of  the  various  cells  that  the 
ferments  may  the  more  readily  act  upon  their  contents ; 
and  at  the  same  time  they  bring  about  subtle  chemical 
changes  that  greatly  increase  the  palatability  of  food- 
stuffs. 

Thorough  mastication  of  the  food  is  important  for  the 
reasons  already  stated,  and  the  cause  of  most  dyspepsias 
may  be  found  in  faulty  habits  of  eating.  Foster  says 
that  in  the  stomach  "  the  natural  bundles  of  meat  and 
vegetables  fall  asunder,  the  muscular  fibres  split  up  into 
disks,  and  the  protoplasm  is  dissolved  from  the  vegetable 
cell "  ;  but,  "  if  the  meat  be  not  chewed  properly,  but 
'bolted,'  the  solvent  gastric  juice  can  only  act  on  the 
exterior  of  the  mass,  while  '  lumps '  offend  the  stomach 
and  arrest  the  gastric  secretion."  Tlie  importance  of 
abstaining  at  meal-time  from  beverages  or  other  sub- 
stances of  too  low  or  too  high  a  temperature  has  already 
been  noted,  and,  as  all  the  enzymes  act  best  at  the  body- 
temperature,  care  should  always  be  had  to  avoid  chilling 
of  the  abdominal  organs  while  digestion  is  under  way. 

Again,  as  the  formation  and  action  of  the  enzymes 
begin  witli  the  ingestion  of  food  and  depend  largely  upon 
a  sufficient  blood-supply  to  tiie  organs  concerned  as  long 
as  digestion  continues,  it  is  essential  that  the  blood-current 
shall  not  Ijc  diverted  from  these  organs  during  this  period 


DIETETIC  RULES.  235 

by  excessive  mental  or  physical  demands,  and  that  a  con- 
dition of  cheerfulness,  repose,  and  rest  should  follow 
every  meal.  Regularity  as  to  the  time  of  meals  and 
the  avoidance  of  too  great  a  tax  upon  any  of  the  organs 
by  over-indulgence  or  intemperance  in  eating  are  likewise 
both  important  matters  and  ones  too  often  neglected. 

It  is  interestins:  to  note  that  in  certain  members  of  the 
vegetable  kingdom  are  to  be  found  enzymes  very  similar 
to  the  normal  ones  of  animal  origin  just  considered,  and 
that  where  the  latter  appear  to  be  deficient  in  quantity  or 
action  these  kindred  ones  may  sometimes  be  used  with 
advantage.  Thus,  in  the  pineapple  and  in  the  papaw  are 
ferments  akin  to  pepsin  or  trypsin,  and  in  the  former 
another  with  the  same  action  as  rennin.  All  are  familiar 
with  the  diastase  of  germinating  seeds  and  its  use  in  the 
making  of  beer ;  but  not  so  common  is  the  knowledge 
that  other  seeds  contain  fat-splitting  enzymes  much  like 
steapsin.  But  though  these  extraneous  digestants  may  be 
valuable  and  advantageous  as  therapeutic  agents  when  au 
actual  lessening:  or  cessation  of  normal  function  makes 
them  necessary,  a  caution  should  be  interpolated  here 
regarding  the  habit  that  may  be  acquired  of  depending 
too  much  upon  them,  especially  by  persons,  otherwise 
healthy,  whose  digestive  functions  are  somewhat  defi- 
cient. A  better  plan  is  to  bring  those  functions  up  to  tiio 
normal  in  strength  and  vigor  by  the  observance  of 
hygienic  rules  and  a  well-considered  method  of  life. 

The  Amount  of  Food  Necessary  to  Life  and 
Health. — Considerable  work  has  been  done  to  determine 
just  what  amount  of  the  proximate  food-principles  the 
average  person  requires  daily,  and  in  this  respect  Mole- 
schott's  tables  are  quite  generally  accepted,  having  been 
constructed  from  data  gained  by  actual  experiment  and 


236  FOOD. 

ulso  by  the  continued  observation  of  the  effects  of  a 
number  of  dietaries.  According  to  these  tables,  a  man 
weighing  160  pounds  and  doing  work  equivalent  to  300 
foot-tons  per  diem  will  need  about  4.6  ounces  of  proteids, 
3  ounces  of  fats,  14.25  ounces  of  carbohydrates,  and  a 
little  more  than  1  ounce  of  salts.  Vaughan  believes  that 
the  average  working-man  in  America  requires  daily,  in 
round  numbers,  not  less  than  four  ounces  of  proteids,  tico 
ounces  of  fats,  and  eighteen  ounces  of  carbohydrates. 
Chittenden  has  recently  claimed  that  four  ounces  of 
proteids  is  considerably  more  than  is  necessary  to  main- 
tain health,  but  the  quantities  given  are  the  ones  generally 
accepted  by  physiologists. 

It  is  essential  that  the  proper  proportion  between  the 
ingested  nitrogen  and  carbon  should  be  maintained,  and 
this  should  be  as  one  of  the  former  io  fifteen  of  the  latter. 

In  addition,  the  individual  needs  from  70  to  100  fluid- 
ounces  of  water  dailv,  a  good  part  of  which,  however,  is 
normally  taken  witli  tlie  food.  It  must  be  remembered 
that  tlie  above  figures  represent  only  average  amounts, 
and  that  climate,  amount  of  exercise,  the  size  and  activity 
of  functional  and  excretory  organs,  and  personal  peculi- 
arities all  serve  to  modify  them  in  the  case  of  any  special 
individual. 

Other  conditions  not  interfering  too  greatly,  any  com- 
bination of  foods  giving  the  above  amounts  of  the  proxi- 
mate principles  at  a  reasonable  cost  will  be  an  economical 
and  healthful  diet,  provided  such  food  is  acceptable  to  the 
palate,  is  digestible,  and  contains  nothing  liannful  to  the 
system.^ 

>  For  such  combinations,  see  Vaughan's  Healthy  Homes  and  Foods 
for  the  Working  Classes;  and  Mrs.  Abel's  Practical,  Sanitary,  and  Econo- 
mic Cooking.  Both  are  essays  published  by  the  American  Public  Health 
Association. 


DAILY  AMOUNT  OF  FOOD  NECESSARY.         237 

Fotliergill  thinks  that,  as  a  rule,  we  take  too  much  pro- 
teid  food,  especially  in  the  form  of  meat,  and  that,  though 
this  goes  in  the  main  for  tissue-repair,  the  latter  requires 
much  less  of  such  food  than  we  ordinarily  suppose,  and 
that  the  system  does  not  need  so  very  much  of  albumin 
or  its  equivalents.  In  this  he  may  be  correct  to  a  certain 
degree,  particularly  as  regards  his  fellow-Englishmen,  who 
are  notorious  meat-eaters,  and  as  to  the  facts  that  tissue- 
waste  is  comparatively  slight  and  that  the  body  frame- 
work rusts  out  rather  than  burns  out.  But  in  addition 
to  the  statements  already  made — that  part  of  our  nitro- 
genous food  regulates  the  demand  for  oxygen,  that  part  is 
doubtless  a  source  of  energy,  and  that  still  another  part 
may  be  converted  into  fat — we  should  also  remember  that 
animal  food  is  a  concentrated  food,  that  much  energy  has 
been  expended  in  converting  and  storing  it  from  the 
vegetable  world,  that  it  is  stimulating,  and  that  our  di- 
gestive organs  resemble  more  closely,  at  least  as  far  as 
comparative  weight  is  concerned,  those  of  the  carnivora 
rather  than  of  the  herbivora.  These  reasons,  as  well  as 
the  fact  that  proteids  make  up  a  considerable  part  of  the 
only  typically  com})lete  food  that  we  have  and  which 
nature  gives  to  the  mammalian  infant,  indicate  that 
we  shoidd  be  as  careful  not  to  use  too  little  as  too  much 
nitrogenous  food. 

The  proteid  portion  of  our  food  is  obtained  from  the 
albumin  of  meat  and  fish,  from  milk  and  eggs,  and  from 
the  gluten  of  cereals  and  the  vegetable  casein  (albumin) 
of  the  leguminous  plants,  such  as  peas,  beans,  etc.  The 
proportion  and  properties  of  the  albuminous  matter  vary, 
of  course,  in  each  of  these,  and  even  in  the  same  sub- 
stances under  different  circumstances ;  but  all  should  be 
taken  into  consideration  and  used  interchangeably  if  we 


238  FOOD. 

wish  to  obtain  the  greatest  variety  and  benefit  in  feeding, 
together  with  due  economy  of  expense. 

In  this  connection  attention  may  again  be  directed  to 
the  notable  fact  that  the  leguminous  plants,  through  the 
aid  of  certain  species  of  bacteria,  are  able  to  absorb  and 
store  up  in  the  form  of  proteids  a  considerable  quantity 
of  nitrogen  from  the  surrounding  atmosphere,  and  that 
tliese  plants  are,  therefore,  an  important  source  of  food- 
supply. 

The  carbohydrates  that  furnish  food  to  the  body  and 
are  one  of  the  sources  of  the  heat  und  energy  upon  which 
muscular  motion  and  vital  activity  depend,  are  practically 
all  derived,  with  the  exception  of  milk-sugar,  from  the 
starches,  sugars,  and  gums  of  the  vegetable  kingdom. 

It  lias  been  shown  that  much  the  greater  part  of  the 
digestion  of  carbohydrate  food  is  due  to  the  action  of 
the  pancreatic  enzyme  amylopsin ;  but  we  should  not 
forget  the  action  of  the  saliva,  nor  that  tliorough  mastica- 
tion greatly  assists  the  subsequent  digestion  by  breaking 
up  the  starch  granules  and  exposing  them  more  freely  to 
the  action  of  the  digestive  juices.  The  latter  object  is 
also  obtained  by  crushing  the  cereals  and  by  cooking  the 
sturch-containing  foods,  for  "  grinding  and  cooking  lessen 
the  labor  of  the  jaws  and  salivary  (and  pancreatic) 
glands." 

After  the  end-products  (dextrose,  levulose,  etc.)  of  carbo- 
hydrate digestion  have  been  absorbed  from  the  alimen- 
tary canal,  part  of  them,  at  least,  are  reconverted  in  the 
liver  into  aniinal  starch  or  glycogen,  and  this  portion  be- 
comes a  part  of  the  body-store  of  fuel.  Fothergill  says: 
"  The  liver  stores  up  from  each  meal  so  much  glycogen 
and  gives  it  off  as  required  ;  otherwise  life  would  only  be 
one  dreary  meal."     Another  and  perhaps  greater  moiety 


FUNCTIONS  OF  THE  CARBOHYDRATES.         239 

of  the  digested  carbohydrates  is  converted  into  fat  and 
stored  as  adipose  tissue  in  various  parts  of  the  body,  as 
a  further  reserve  of  fuel  for  any  emergency.  "  Many 
authorities  state  that  fat  is  formed  directly  from  carbo- 
hydrates, and  the  weight  of  evidence  appears  to  favor  this 
view ;  but  whether  it  is  so  formed  directly,  or  indirectly 
by  retarding  the  metabolism  of  the  fatty  and  proteid  con- 
stituents of  the  food,  there  is  no  doubt  that  the  consump- 
tion of  carbohydrates  results  in  the  formation  of  fat  within 
the  body." '  Moreover,  "  whatever  the  mixture  of  fats 
taken  in  as  food,  the  fat  of  the  body  always  has  the  same 
composition  ;  this  fact  agrees  with  the  conclusion  that  the 
metabolism  and  deposition  of  fat  in  the  body  are  due  to 
cell  activity,  and  that  the  fat  comes  in  part  from  the  pro- 
teid and  part  from  the  carbohydrate  foods."  ^ 

Another  important  function  of  the  carbohydrate  foods 
is  the  formation  by  their  metabolism  in  the  body  of  lactic 
and  other  acids,  which  are  of  the  greatest  value  in 
nutrition  and  in  maintaining  the  normal  reactions  of  the 
body-fluids.  This  is  perhaps  one  of  the  chief  reasons  why 
fats  and  carbohydrates  are  not  interconvertible  in  any 
prolonged  dietary. 

Fat  is  essentially  a  compound  of  glycerin  with  one  or 
more  fatty  acids,  usually  stearic,  palmitic,  and  oleic.  The 
digestibility  of  a  fat  largely  depends  upon  its  being  fluid 
at  the  body-temperature ;  therefore,  as  the  melting-point 
of  stearin  is  higher  than  this,  the  more  of  it  that  a  fat 
contains,  the  less  digestible  and  nutritious  will  the  latter 
be.  For  this  reason  butter  is  more  digestible  than  suet, 
lard  than  mutton-fat,  etc.,  and  the  more  assimilable  ood- 
liver  oil  is  that  from  which  the  stearin  has  been  removed. 

Fat  for  food  is  derived  from  vegetable  as  well  as  ani- 
1  Notter  and  Firth,  Treatise  on  Hygiene,  p.  254.  "^  Ibid.,  p.  2.53. 


240  FOOD. 

mal  sources,  many  seeds  and  nuts  and  some  cereals,  as 
oats  and  corn  (maize),  containing  much  fat.  By  improved 
methods  it  is  becoming  possible  to  supply  fats  in  purer, 
cheaper,  and  more  agreeable  forms,  so  that  they  may  now 
be  freely  used  even  by  the  poor,  the  very  class  that  needs 
them  most. 

Under  normal  conditions  it  is  probable  that  the  body- 
fat  or  adipose  tissue  is  almost  never  derived  from  the 
fat  in  food,  but  rather,  as  stated,  from  the  proteids  and 
carbohydrates ;  but  fat  is  also  an  essential  part  of  tissue- 
structure,  making  up  more  than  one-fifth  of  the  solid 
matter  of  the  brain  and  nerve  tissues  and  one-sixth  of 
muscle,  and  possibly  serving  as  fuel  Avhen  the  cell-con- 
tents are  oxidized ;  and  it  is  probable  that  this  fat  of 
active  tissues  comes,  at  least  in  part,  from  that  ingested  as 
food.  The  writer  has  already  hinted  at  the  possibility  of 
a  combination  of  the  newly  absorbed  fat  with  the  argon 
of  the  atmosphere  in  the  lungs  and  the  consequent  forma- 
tion of  new  cells  or  vital  material.  It  is  also  probable 
that  the  digested  fats  or  their  acids  enter  into  coml)ina- 
tion  with  certain  organic  substances  in  the  intestinal 
canal  or  in  the  lymph  or  blood,  the  resulting  compounds 
being  intermediate  to  ones  still  higher  and  essential  in  the 
structure  of  vital  and  active  cells.  Adami,'  has  shown 
that  in  fatty  degenerations  and  other  pathological  proc- 
esses, as  well  as  in  many  normal  tissues,  so-called  "mye- 
lin ghjbules"  are  to  be  found.  These  myelin  globules 
prove  to  be  compounds  of  oholesterin  or  of  cholin  or 
neurin  with  fatty  acids.  Moreover,  lecithins,  which  are 
found  in  every  cell  and  abundantly  in  the  brain  and 
nerves,  as  well  as  in  ))lood  corijiiscles  and  lympli,  dissociate 

1  The.  Myelins  and  PoteuHal  Fluid  Crystalline  Bodies  of  the  Onjanism, 
Journal  of  the  American  Medical  Association,  Feb.  9,  1907,  pp.  463-469. 


FUNCTIONS  OF  FAT  IN  THE  DIET.  241 

in  breaking  up  into  fatty  acids,  glycerophosphoric  acid 
and  cholin,  or,  according  to  Carbone,  into  fatty  acids, 
neutral  fats  and  cholesterin.  Beyond  the  lecithins  is  pro- 
tagon,  "  which  is  obtained  especially  from  the  brain  and 
is  a  crystalline  body  containing  lecithin  and  cerebrin." 
Thus  it  is  seen  how  the  derivatives  from  the  fat  in  the 
diet  become  incorporated  as  component  parts  of  the  most 
complex  tissues  and  organs.  In  any  case,  however,  fat 
is  a  very  important  part  of  a  man's  diet,  for  not  only 
is  a  small  quantity  necessary  to  the  digestion  of  proteids, 
causing  the  formation  in  the  body  of  larger  amounts  of 
fat  than  the  quantity  ingested  and  greatly  improving  the 
physical  condition ;  but  it  may  be  and,  when  occasion 
requires,  undoubtedly  often  is  used  directly  as  fuel  with- 
out first  being  stored  in  the  tissues. 

As  fat  is  a  concentrated  fuel-food,  it  is  to  be  used  freely 
when  we  want  to  keep  the  body  warm  or  when  we  need 
extra  force  for  any  increased  exertion.  "  On  a  diet  rich 
in  fat  great  muscular  effort  can  be  undergone  with  but 
little  destruction  of  muscular  tissue,  and  without  increased 
urea  discharge."  The  object  of  fat  in  the  diet,  then, 
may  be  said  to  be  to  give  heat  and  energy  as  fuel,  and, 
when  necessary,  to  aid  in  the  repair  or  building  up  of 
active  tissue. 

The  constructive  property  of  fat  is  especially  valuable 
in  the  treatment  of  all  wasting  diseases,  especially  phthisis. 
Fothergill  emphatically  declares  that  "  the  great  food  for 
the  strumous  is  fat,"  and  also  says  :  "  Whenever  there 
is  any  tendency  to  tubercle  the  individual  should  learn 
to  eat  fat,  just  as  a  seafaring  man  learns  to  swim.  As  a 
physician  to  a  chest  hospital,  I  have  learned  to  dread  the 
announcement  that  fat  is  no  longer  taken,  especially  if  the 
individual  is  of  strumous  build,  with  a  small,  narrow 
16 


242  FOOD. 

chest.  In  my  opinion,  the  existence  of  a  considerable 
area  of  affected  lung  where  the  digestive  powers  keep  up 
is  less  fraught  with  evil  and  less  prognostically  significant 
than  intractable  wasting  with  very  little  disease  in  the 
lung."  In  this  connection,  note  that  an  excess  of  pro- 
teids  in  the  diet  causes  a  more  rapid  oxidation  of  fat,  and 
that  an  excess  of  fat  or  of  carbohydrates  lessens  the  ab- 
sorption of  oxygen  and  the  oxidation  of  both  fats  and 
proteids.  Also,  that  the  free  use  of  fluids  is  thought  to 
favor  an  increase  in  the  quantity  of  fat  deposited  in  the 
body. 

Fat  is  practically  indigestible  in  the  stomach,  and  some 
stomachs  cannot  tolerate  it,  especially  when  taken  with 
other  food ;  although  usually  a  little  fat  assists  in  the 
digestion  of  proteids  by  stimulating  the  secretion  of  the 
gastric  juice.  Cases  occur  not  rarely  in  which  it  is  neces- 
sary that  comparatively  large  quantities  of  fat  should  be 
ingested  and  yet  in  which  there  is  apparently  decided  gas- 
tric intolerance  of  it.  In  such  event  success  is  often  to 
be  attained  by  giving  the  fat  some  little  time  after  the 
regular  meals,  when  the  gastric  digestion  is  approaching 
completion  and  the  chyme  is  being  passed  out  of  the 
stomach  to  be  further  suljjected  to  the  action  of  the  intes- 
tinal digestants.  It  may  also  be  well  to  emulsify  it 
partially  or  wholly,  especially  if  there  be  faulty  secretion 
of  bile  and  pancreatic  juice,  and  sometimes  to  disguise  its 
taste  with  agreeable  aromatics  or  flavors.  In  this  way 
there  is  generally  but  little  trouble  in  administering  fats, 
even  such  as  those  which,  like  cod-liver  oil,  have  a  dis- 
agreeable taste  and  odor.  Failing  in  this,  we  may  still 
resort  to  inunctions,  preferably  of  predigested  or  emulsi- 
fied fats,  and  often  with  considerable  advantage,  since  it 
has  been  experimentally  shown  that  after  passing  through 


FUNCTIOXS   OF  DIFFERENT  SALTS.  243 

the  skin  fat  may  be  taken  up  by  the  subcutaneous  lymph- 
atics and  later  be  oxidized  or  metabolized  almost  as  com- 
pletely as  if  it  had  entered  the  system  by  way  of  the 
intestinal  canal  and  thoracic  duct. 

Certain  salts  in  definite  proportions  are  necessary  for 
the  maintenance  of  health  in  the  body.  "  Lime,  chiefly 
in  the  form  of  phosphate,  is  absent  from  no  tissue, 
and  there  is  reason  to  think  that  no  cell-growth  can  go 
on  without  it."  Even  the  bacteria  must  have  earthy 
phosphates  for  the  purposes  of  growth.  Chlorine,  derived 
largely  from  the  sodium  chloride  of  food,  is  necessary  to 
form  the  hydrochloric  acid  of  the  gastric  juice,  the  chlo- 
rides also  keeping  in  solution  the  globulins  of  the  blood 
and  body-fluids  and  helping  to  dissolve  the  albumin. 
Phosphorus  is  necessary  in  the  formation  of  the  lecithin 
of  nerve-tissues,  as  well  as  for  the  phosphates  above  men- 
tioned, and  those  of  potassium,  magnesium,  etc.,  which 
go  to  form  bone.  Potassium  salts  maintain  the  alkalinity 
of  the  solid  tissues,  and  sodium  salts  that  of  the  bodv- 
tluids.  Iron  is  essential  for  the  construction  and  ntitri- 
tion  of  the  blood-corpuscles,  though  small  quantities  of  it 
are  to  be  found  in  almost  every  other  tissue. 

But  not  only  must  the  above  inorganic  salts  be  given 
in  proper  supply,  but  also  certain  ones  of  organic  nature, 
in  order  to  prevent  conditions  of  malnutrition  or  disease. 
Those  especially  which  are  changed  to  form  carbonates, 
as  the  lactates,  tartrates,  etc.,  or  their  respective  acids, 
help  to  maintain  the  alkalinity  of  the  system  and  appear 
to  be  most  essential,  as  a  scorbutic  condition  seems  to  be 
inevitably  created  or  fostered  by  their  absence.  There  is 
also  some  evidence  that  certain  gouty  conditions  may  be 
due  to  the  removal  of  the  natural  vegetable  salts  by  im- 
proper methods  of  cooking.    The  fact  of  the  carbohydrates 


244  FOOD. 

being  an  important  source  of  these  organic  acids  and  salts 
has  already  been  mentioned. 

Lastly,  with  many  of  our  foods  we  require  the  addition 
of  certain  flavors,  condiments,  etc.,  which,  though  they 
have  little  or  no  real  food-value  in  themselves  in  the 
sense  of  repairing  tissue  or  furnishing  energy,  do  much 
good,  when  not  abused,  by  making  the  food  more  pala- 
table, by  stimulating  the  secretion  of  the  digestive  fluids, 
and  by  acting  as  carminatives.  These  condiments  should 
not  be  omitted  from  the  food  of  the  sick  or  convalescent, 
for  they  have  a  value  of  their  own,  and  are  "  agreeable 
to  the  palate  and,  in  moderation,  good  for  the  digestive 
organs.'' 

As  a  review  of  the  preceding  statements,  the  fol- 
lowing quotation,  from  Xotter  and  Firth,^  may  be  of 
value : 

"  With  regard  to  the  necessity  for  all  four  classes  of 
aliments,  it  can  be  affirmed  with  certainty  that  (putting 
scurvy  out  of  the  question)  men  can  live  for  some  time 
and  can  be  healthy  with  a  diet  of  proteids,  fats,  salts,  and 
water.  But  special  conditions  of  life,  such  as  great  exer- 
cise or  exposure  to  very  low  temperature,  appear  to  be 
necessary,  and  under  usual  conditions  of  life  health  is  not 
very  perfectly  maintained  on  such  a  diet.  It  has  not  yet 
been  shown  that  men  can  live  in  good  health  on  proteids, 
carbohydrates,  salts  and  water,  without  fat. 

"  The  exact  effect  produced  by  the  deprivation  of  any 
one  of  these  classes  is  not  yet  known.  Xn  excess  of  the 
proteids  causes  a  more  rapid  oxidation  of  fat,  while  an 
excess  of  fat  lessens  the  absorption  of  oxygen  and  hinders 
the  metamorphosis  of  both  fat  and  albuminous  tissues. 
Tlie  carljohyd rates  have  tlie  same  effect  when  in  excess, 
'  Treatise  on  Hygiene,  p.  256. 


MILK.  245 

and  appear  to  lessen  the  oxidation  of  the  two  other 
classes. 

"  It  is  generally  admitted  that  the  success  of  Banting's 
treatment  of  obesity  is  owing  to  two  actions  :  the  increased 
oxidizing  effect  on  fat  consequent  on  the  increase  of  meat 
(especially  if  exercise  be  combined),  and  the  lessened 
interference  with  the  oxidation  of  fat  consequent  on  the 
deprivation  of  starches, 

"  Health  cannot  be  maintained  on  proteids,  salts,  and 
water  alone ;  but,  on  the  other  hand,  it  cannot  be  main- 
tained without  them." 

It  will  be  impossible  to  go  into  details  concerning  all 
the  articles  commonly  used  as  foods,  but  there  are  certain 
facts  that  should  be  well  known  and  which  cannot  properly 
be  omitted  from  a  work  of  this  kind. 

Milk  is  a  typical  food-stuff,  complete  in  itself,  in  that  it 
contains  all  the  food-principles,  and  these  in  nearly  the 
proper  proportion,  at  least  for  infant  life.  The  casein  and 
albumin  represent  the  proteids ;  the  cream,  the  fats ;  and 
the  lactose  or  milk-sugar  is  a  concentrated  carbohydrate — 
all  being  in  combination  with  sufficient  salts  and  water. 

]\Iilk  should  constitute  almost  the  sole  food  of  infants 
during  the  earlier  months  of  life  ;  and  that  it  is  capable  of 
sustaining  adult  life  almost  indefinitely,  especially  where 
there  is  little  demand  for  heat  or  the  expenditure  of  force, 
has  been  shown  in  numerous  instances.^  Coplin  and 
Bevan  mention  the  case  of  a  patient  who  lived  and  thrived 
on  milk  alone  for  over  thirteen  months,  and  of  another 
who  lived  for  three  years  on  the  same  diet.      But  the 

^  It  is  understood,  of  course,  that  in  order  to  be  a  proper  food  for 
young  infants,  cows'  milk  must  be  modified  so  as  to  resemble  human 
milk  as  nearly  as  possible,  and  so  as  to  give  the  proportion  of  the  respec- 
tive food-principles  which  each  particular  case  may  need. 


246  FOOD. 

limited  proportion  of  carbohydrates,  even  though  concen- 
trated, i^  not  all-sufficient  for  the  maintenance  of  great 
vital  activity,  and  for  persons  in  ordinary  life  some  addi- 
tion to  the  diet  is  necessary. 

The  albumin  of  milk  is  coagulateil  l>v  heat.  Ijut  the 
casein,  which  constitutes  the  greater  part  of  the  prnteid 
element,  is  clotted  bv  an  acid  or  bv  an  enzyme,  such  as 
rennin  ;  and  as  both  acid  and  rennin  are  ]iresent  in  normal 
ga.stric  juice,  it  would  seem  that  the  preliminary  coagulation 
of  casein  was  essential  to  its  proper  digestion.  It  should  be 
remembered,  however,  that  the  casein  of  cows'  milk  forms 
a  much  harder  and  firmer  clot  than  does  that  of  human 
milk,  and  that  the  former  should,  therefore,  never  be 
hastily  introduced  into  the  stomach  in  large  volumes,  but 
should  rather  be  taken  slowly  and  preferably  with  other 
food  which  will  help  to  divide  the  curd  mechanically. 
In  the  feeding  of  children,  an  alkali,  such  as  lime-water, 
is  thought  to  soften  the  curd  when  mixed  with  the  milk, 
and  possibly  to  facilitate  digestion. 

Outside  of  the  body,  fermentative  changes  due  to  certain 
bacteria  may  convert  tlie  milk-sugar  into  lactic  acid,  which 
coagulates  the  casein  and  "  sours "  the  milk.  Another 
peculiarity  of  casein  is  the  tenacity  with  which  it  holds 
large  quantities  of  phosphate  of  lime,  one  of  the  most 
valuable  of  food-salts. 

Sometimes  it  is  advantageous  or  necessary  to  predigest 
milk  for  infants  or  sick  persons,  but  if  the  digestion  be 
carried  beyond  a  certain  point,  the  consequent  peptones 
and  albumoses  will  give  the  milk  a  bitter  and  disagreeable 
taste.  In  the  feeding  of  infants  it  must  not  be  forgotten 
that  the  percentage  composition  of  human  milk  is  different 
from  that  of  cows'  milk,  and  that  the  latter  will  need 
dilution  to  decrease  the  proteid   proportion,   but   an    in- 


CARE  OF  MILK:   CREAM.  247 

crease  of  fat  and  carbohydrates.  As  a  child  grows  older 
and  more  active,  it  becomes  necessary  to  add  to  the 
milk  additional  carbohydrates,  which  should  be  easy 
of  digestion  and  soluble,  milk-sugar  and  predigested 
starches  in  the  form  of  maltose  and  its  allies  being  pref- 
erable. 

Milk  should  always  be  kept  as  cool  as  possible  and  in 
closed  vessels,  not  only  to  prevent  the  absorption  of  dis- 
agreeable odors  and  harmful  gases,  which  it  is  very  prone 
to  do,  but  to  exclude  dirt  and  bacteria  as  well.  As  it  is 
an  excellent  culture-medium,  and  as  it  is  commonly  liable 
to  be  exposed  to  contamination  by  organisms  from  many 
sources  before  it  reaches  the  consumer,  fermentative  or 
other  harmful  chemical  changes  are  almost  certain  to 
occur  in  it  if  the  temperature  conditions  are  at  all  favor- 
able. For  this  reason  it  is  necessary  that  the  greatest 
care  should  be  used  in  the  handhng  of  the  milk  from  the 
time  it  leaves  the  cow  until  it  is  used,  and,  for  the  feeding 
of  children  and  whenever  there  is  any  possibility  of  it 
being  the  carrier  of  disease  germs  of  any  kind,  it  should 
be  properly  sterilized  and  then  kept  sterile  until  used. 
In  fact,  sterilized  milk,  modified  to  resemble  the  human 
secretion,  will  usually  be  superior  to  any  other  artificial 
food  for  infants,  but  the  sterilization  should  always  be 
done  before  fermentation  has  begun  and  harmful  products 
have  been  developed  in  the  milk.  The  sterilization  may 
slightly  alter  the  taste  and  other  properties  of  the  milk  by 
coagulating  the  albumin,  but  it  is  doubtful  whether  it 
makes  any  real  change  in  its  digestibility. 

The  cream  of  milk  is  fat  in  its  most  digestible  and  ac- 
ceptable form,  and  should  not  be  removed  from  milk  if 
the  latter  is  to  be  used  as  food.  If  the  milk  seems  to  be 
too  rich,  it  may  be  advisable  to  skim  it,  giving  it  in  some 


248  FOOD. 

form  or  other  with  the  regular  meal,  and  reserving  the 
cream  until  a  couple  of  hours  or  so  later,  when  gastric 
digestion  is  approaching  completion.  One  may  also  often 
avoid  the  use  of  cod-liver  oil  and  similar  fats  by  taking 
cream — either  plain  or  whipped  and  flavored — in  this  way 
some  little  time  after  the  meals. 

Skimmed  milk  and  buttermilk  may  be  used  freely  as 
beverages,  as  both  are  refreshing  and  healthful  with  some 
little  food-value  j  buttermilk  is  also  acceptable  to  many 
persons  on  account  of  its  lactic  acid.  "  Koumiss "  and 
''kefir"  are  both  prepared  from  milk  through  the  action 
of  certain  fermentative  organisms,  which  also  bring  about 
a  partial  digestion  of  the  casein.  Each  contains  carbonic 
and  lactic  acids,  though  in  different  proportions,  some  pep- 
tones or  albumoses,  and  a  very  little  alcohol.  They  are 
wholesome,  agreeable  to  most  palates,  and  are  usually 
retained  and  utilized  by  stomachs  rebellious  to  almost  all 
other  foods.  Furthermore,  MetchnikoflF '  strongly  advo- 
cates their  use,  since  lactic  acid  and  the  micro-organisms 
that  cause  its  formation  are  antagonistic  to  the  microbes 
of  putrefaction,  which  multiply  only  in  alkaline  substances. 
The  beverages  mentioned,  therefore,  tend  to  prevent  the 
introduction  into  the  intestinal  canal  of  such  putrefactive 
germs  and  the  development  there  of  ptomains  and  other 
poisonous  products  of  decomposition  which,  when  ab- 
sorbed into  the  circulation,  give  rise  to  the  manifold 
symptoms  of  auto-intoxication. 

Milk  may  be  a  factor  in  the  causation  of  disease  in  a 
number  of  ways.  Large  and  tough  curds  of  cows'  milk 
in  the  stomach  often  cause  mechanical  irritation  and  indi- 
gestion, especially  in  young  children,  and  the  products  of 
the  fermentative  action  already  referred  to  are  a  frequent 
1  The  Nature  of  Man,  chapter  x. 


RELATION  OF  MILK  TO  ]5lSEASE.  249 

source  of  serious  intestinal  disorders ;  while  if  further 
decomposition  occurs,  a  very  poisonous  ptomain,  called 
tyrotoxicon,  is  apt  to  be  developed  and  to  cause  even  fatal 
results  to  those  using  the  milk.  This  same  substance  is 
also  liable  to  occur  in  any  milk-product,  such  as  cheese 
or  ice-cream,  and  is  usually  the  cause  or  agent  in  the  cases 
of  poisoning  by  such  products  that  are  so  frequently 
reported. 

Again,  the  active  principles  of  plants  which  the  cow 
has  eaten  may  be  transmitted  by  the  milk  and  produce 
their  physiological  effects.  But  a  graver  question  is 
whether  disease  may  be  transmitted  directly  from  the 
animals  to  man  by  this  almost  universal  food-stuff.  Every 
one  knows  that  the  milk  from  sick  cows  may  cause 
marked  disturbance  of  health,  and  there  is  fair  evidence 
that  cattle  are  subject  to  certain  diseases  identical  with 
or  very  similar  to  human  maladies,  the  milk  serving  as  a 
carrier  for  the  contagium. 

Scarlet  fever  and  diphtheria  may  be  mentioned  as 
diseases  suspected  of  being  transmitted  in  this  way,  and 
there  seems  to  be  no  longer  any  doubt  in  regard  to  tuber- 
culosis. Though  some  authorities  still  question  whether 
this  latter  disease  can  be  thus  transmitted  unless  the  milk- 
glands  themselves  are  affected,  the  great  prevalence  of  the 
disease  among  cattle  and  experimental  evidence  both  make 
it  certain  that  milk  is  often  the  means  of  transmitting  the 
infection,  and  many  believe  that  by  far  the  larger  number 
of  the  many  cases  of  infantile  tuberculosis  have  origin  from 
this  source.  The  condemnation  and  destruction  of  all  cattle 
that  show  symptoms  of  tubercular  infection  is  certainly 
one  of  the  most  important  and  effective  methods  of  check- 
ing the  spread  of  and  eliminating  this  very  prevalent  and 
deadly  malady.     The  use  of   inoculations  of   tuberculin 


250  FOOD. 

as  a  means  of  diagnosis  has  materially  contributed  to  this 
end,  for  by  its  aid  the  presence  of  the  disease  is  often 
indicated  in  many  animals  that  have  as  yet  evinced  no 
physical  signs  of  the  disease. 

A  British  Royal  Commission  ^  have  recently  found, 
they  say,  "that  milk  containing  bovine  tubercle  bacilli 
can,  by  feeding,  produce  tuberculosis  in  apes,  and  they 
have  no  doubt  that  many  cases  of  human  tuberculosis, 
especially  in  children,  are  due  to  this  germ.  The  same 
conclusions  had  been  reached  by  the  United  States  Agri- 
cultural Department's  investigators.  The  importance  of 
proper  bacteriologic  analyses  of  milk  and  the  inspection 
of  dairies  cannot  be  sufficiently  emphasized,  and  it  is  very 
possible  that  while  the  milk  of  tuberculous  cows  may  be 
comparatively  innocuous  to  adults  of  fair  resisting  powers, 
it  may  be  extremely  dangerous  to  young  children  and 
those  having  a  predisposition  to  tuberculous  infection." 

Milk,  like  other  food-stuffs,  may  also  become  a  disease- 
carrier  through  infection  from  dust  and  disease  germs, 
especially  in  the  vicinity  of  places  where  infectious  matter 
is  allowed  to  dry,  become  pulverized,  and  to  be  taken  up 
into  the  atmosphere  by  winds  and  air-currents.  But  a 
more  common  danger  is  through  carelessness  in  handling 
by  infected  persons  or  by  the  admixture  with  it  of  water 
containing  disease  germs.  Epidemics  of  diphtheria,  scar- 
let fever,  typhoid  fever,  and  cholera  have  all  been  traced 
to  contaminated  milk-supplies,  and  it  is  a  question  whether 
many  of  the  more  or  less  local  outbreaks  in  cities  are 
not  of  this  character.  The  writer  is  personally  cogni- 
zaiil  of  five  cases  of  undoubted  scarlet  fever  that  occurred 
almost  simultaneonsly  in  one  locality  and  in  which,  ap- 
I)arently,  the  only  common   source  was  the  milk-supply. 

I   Jouriiiil  of  till!  American  Minlical  Association,  VvhA),  1907,  p.  528. 


RELATION  OF  MILK  TO  DISEASE.  251 

He  was  unable  to  discover  that  there  had  been  any  illness 
either  among  the  cattle  or  in  the  family  of  the  milkman  in 
question,  but  he  has  always  felt  that  there  was  consider- 
able evasion  in  replying  to  the  inquiries  made.  He  also 
has  knowledge  of  a  localized  epidemic  of  typhoid  fever 
due  to  the  infection  of  a  common  milk-supply.  In  this 
instance  the  dissemination  of  the  disease  was  traced  to 
the  use  of  a  rubber  tube  for  siphoning  the  milk  from  a 
receiving  can  to  the  distributing  jars,  the  dairyman  and 
his  assistants  exhausting  the  air  from  the  same  by  suction 
by  the  mouth.  At  the  time  this  was  discovered  the 
dairyman  and  at  least  one  of  his  men  were  ill  with  typhoid 
fever  in  a  hospital. 

NeAvman  states  that  since  1857  more  than  one  hundred 
and  sixty  epidemics  of  typhoid  fever  have  been  traced 
to  a  polluted  milk-supply  and  quotes  Schuder  as  saying 
"that  17  per  cent,  of  all  typhoid  epidemics  are  due 
to  the  consumption  of  infected  milk."  Moreover,  New- 
man counts  up  "  some  thirty  outbreaks  of  milk-borne 
diphtheria"  and  some  seventy  of  scarlet  fever,  and 
also  says  that  "  there  are  three  (other)  very  common 
diseases  in  which  milk  has  been  proved  to  plav  a  not 
inconsiderable  part,  viz.,  thrush,  sore  throat,  and  diar- 
rhoea." He  gives  the  following  characteristics  of  milk- 
borne  epidemics  :  ^ 

(a)  Tlicre  is  a  special  incidence  of  the  disease  upon  the 
track  of  the  implicated  milk-supply.  It  is  localized  to 
such  areas. 

(b)  Better-class  houses  and  persons  generally  suffer 
most. 

(c)  Milk  drinkers  are  chiefly  affected,  and  those  suffer 
most  who  are  large  consumers  of  raw  milk. 

'  Bacteriology  and  the  Public  Hcaltli,  third  ed.,  p.  218. 


252  FOOD. 

(d)  Women  and  children  suffer  most,  and  frequently 
adults  suffer  proportionately  more  than  children. 

(e)  Incubation  periods  are  shortened. 

(/)  There  is  a  sudden  onset  and  a  rapid  decline. 

(g)  Multiple  cases  in  one  house  occur  simultaneously. 

(h)  Clinically,  the  attacks  of  disease  are  often  mild, 
contact  infectivity  is  reduced,  and  the  mortality  rate  is 
lower  than  usual. 

Experience  is  also  rapidly  accumulating  that  infecting 
germs  are  implanted  upon  or  in  many  foods  by  house-flies, 
roaches,  and  other  insects,  as  well  as  by  larger  vermin, 
and  even  domestic  animals,  such  as  dogs  and  cats. 
Typhoid  bacilli  having  been  obtained  from  the  bodies  of 
flies  from  a  house  where  eight  cases  of  typhoid  fever  had 
occurred,  further  experiments  showed  that  flies  fed  with 
these  germs  are  able  to  convey  them  to  other  objects  for 
as  long  as  twenty-three  days  afterward.  The  bacilli  have 
also  been  found  on  the  heads,  legs,  and  wings  of  flies  five 
days  after,  and  in  their  intestines  nine  days  after  such 
feeding.^  Consequently,  every  efibrt  should  be  made  to 
])rotcct  food-supplies  of  all  kinds  from  such  contami- 
nation by  insects  and  vermin,  especially  in  time  of  epi- 
demics, for  we  should  realize  that  though  most  of  the 
cases  of  an  ejiidemic  may  arise  from  a  common  source, 
such  as  a  ])ollutcd  water-supply,  there  will  be  numerous 
sporadic  cases  of  which  the  infection  has  been  transmitted 
as  above. 

The  })ossibility  of  milk  as  a  source  of  danger  to  health 
having  been  shown,  the  lessons  to  be  had  are  these  :  that 
not  only  nnist  there  be  the  greatest  care  in  the  handling 
and  keeping  of  milk  until  it  is  consumed,  but  there  must 
also    be    frequent  and   careful   inspection  of  the  animals 

1  Fickcr,  Archives  of  Hygiene,  1903,  xlvi.,  p.  274. 


USE  OF  PRESERVATIVES:   CHEESE.  253 

from  which  it  comes  and  of  their  environment ;  that  no 
milk  from  any  diseased  cow  should  ever  be  used  as  food ; 
that  wherever  there  is  the  suspicion  or  possibility  of  the 
milk  being  contaminated  with  disease  germs,  it  must  be 
thoroughly  sterilized,  and  that  any  change  from  its  normal 
condition  should  also  forbid  its  use. 

Fortunately,  good  milk  can  almost  always  be  had  so 
cheaply  and  readily  that  no  serious  hardship  inures  by  the 
strict  observance  of  these  rules,  and  the  public  should  be 
educated  to  demand  as  well  as  to  pay  fairly  for  pure  milk 
from  healthy  animals,  these  matters  being  even  more 
important  than  that  the  quality,  as  shown  by  analysis, 
should  always  be  up  to  a  certain  standard. 

Good  milk  in  bulk  should  be  opaque,  of  clear  ivory- 
white  color,  should  have  no  peculiar  smell  or  taste  nor  leave 
any  deposit  on  standing.  Nor  should  it  show  any  change 
in  taste  or  appearance  upon  boiling,  excepting  the  forma- 
tion of  the  slight  skin  of  coagulated  albumin  due  to  the 
heating.  Details  regarding  the  composition  of  milk  and 
the  methods  for  its  examination  will  be  found  in  the  final 
chapter  of  this  volume. 

The  addition  of  preservatives  to  milk  is  very  common, 
and  should  be  discountenanced,  not  only  because  they  are 
usually  added  in  quantities  harmful  or  prejudicial  to 
health,  but  also,  and  almost  more  important,  because  milk 
should  be  supplied  to  consumers  in  such  a  condition  and 
state  as  not  to  need  the  preservative,  and  the  presence  of 
the  latter  is  therefore  suspicious.  The  same  reasons 
also  justify  the  condemnation  of  the  use  of  artificial 
coloring-matters.  The  chemicals  commonly  used  as  pre- 
servatives are  boric  acid,  salicylic  acid,  and  formalde- 
hyde. Of  these,  the  salicylic  acid  is  probably  most 
harmful,  as  the   habitual   ingestion  of  even  a  moderate 


254  FOOD. 

quantity  is  apt  to  be  deleterious  to  the  kidneys.  (See 
Chapter  XIV.) 

Cheese  is  a  most  valuable  food-stuff,  and,  as  a  milk- 
product,  may  be  considered  at  this  ti.me.  Good  cheese 
usually  contains  twice  as  much  nitrogen  and  three  times 
as  much  fat  as  the  same  weight  of  meat,  but  many 
persons  apparently  find  it  difficult  of  digestion  and  can 
eat  but  little  of  it.  This  is  perhaps  because  the  nutri- 
ment is  so  concentrated  and  because,  as  usually  eaten,  it 
forms  in  the  stomach  a  tough  or  pasty  solid  lump  into 
W'liich  the  gastric  secretion  cannot  penetrate.  Mattieu 
AVilliams  has  remarked  that  we  habitually  use  cheese  in 
the  conditions  in  wdiich  it  is  most  indigestible — either  in 
its  raw  state  or  cooked  into  a  leathery  mass — and  he  asserts 
that  if  the  cooking  is  such  that  it  is  thoroughly  mixed 
with  other  articles  of  food,  or  if  it  be  masticated  with 
other  food,  so  that  this  commingling  of  particles  takes 
place,  it  will  be  found  to  be  quite  digestible  by  almost 
every  one.  He  also  advises  the  addition  of  a  small 
amount  of  potassium  carbonate  in  the  cooking,  as  this 
favors  solution  of  the  casein  and  replaces  that  salt  which 
is  removed  in  the  whey.  As  a  food,  only  cheese  made 
from  whole  milk,  or  from  that  to  which  extra  cream  has 
been  added,  satisfies  all  requirements,  and  skim-milk 
cheeses  are  decidedly  less  nutritious  than  those  having  the 
full  proportion  of  fat. 

Butter,  consisting  as  it  does  largely  of  the  fat  of  milk, 
is  a  higlily  nutritious  article  of  food  and  one  of  the  most 
digestible  of  its  class.  It  should  be  pure,  sweet  and  free 
from  rancidity,  and  while  some  of  the  substitutes  offered 
in  its  stead  are  entirely  wholesome,  they  should  never  be 
sold  as  butter  or  used  to  adulterate  it.  Neither  should 
butter  contain  an   excess  of  water  nor  of  casein,  as  its 


EGGS:  MEAT.  255 

food-value,   weight    for    weight,    is    thereby    accordingly 
lessened. 

Eg"g"S  yield  almost  their  full  weight  of  food  in  a  con- 
centrated and  very  digestible  condition,  and  are  valuable 
on  this  account,  as  well  as  for  their  palatability  and  their 
value  in  the  preparation  of  many  dishes.  Although  con- 
taining practically  no  carbohydrates,  they  have  sufficient 
food-material  in  themselves  for  the  complete  development 
of  the  living  chick  with  the  aid  of  nothing  external 
except  the  oxygen  which  passes  through  the  shell :  the 
lack  of  the  carbohydrate  element,  ordinarily  one  of  the 
essential  food-principles,  is  supjDlied  by  the  heat  from  the 
mother  hen  or  incubator,  which  is  sufficient  for  the 
development  and  maintenance  of  the  vital  processes,  since 
the  unhatched  creature  wastes  almost  no  energy  in  physi- 
cal activity. 

The  white  of  egg  is  almost  pure  albumin  with  a  little 
water  and  some  salts  ;  the  yolk  contains  about  30  per 
cent,  of  fat  and  some  albumin.  The  albumin  coagulates 
at  about  170°  F.,  but  if  it  is  exposed  to  a  still  higher 
temperature  for  any  but  a  very  short  period  of  time,  it 
becomes  hard  and  difficult  of  digestion.  A  so-called 
"  soft-boiled "  egg  is  scarcely  more  difficult  of  digestion 
than  an  uncooked  one,  and  is  certainly  more  palatable  to 
almost  every  one. 

Eggs,  milk,  and  cheese  may  be  made  into  many  nutri- 
tious and  palatable  combinations  which  furnish  food 
especially  agreeable  to  the  sick,  as  M'ell  as  to  those  whose 
appetite  and  digestive  functions  have  not  been  impaired. 
~~-Meat. — Good  meat,  when  deprived  of  its  contained 
water,  is  a  concentrated  food,  and  is  used  not  only  on 
account  of  the  large  amount  of  nutriment  it  contains,  but 
also  for  its  rich  and  agreeable  flavor.     It  represents  much 


256  FOOD. 

vegetable  matter  converted  into  its  present  palatable  and 
more  digestible  form  by  the  metabolic  activity  of  the  ani- 
mals from  which  it  came.  It  contains  all  the  essential 
food-principles,  the  carbohydrates,  however,  being  present 
as  muscle-sugar  or  inosite  and,  as  in  milk,  in  very  small 
proportion.  In  all  fresh  meat  there  is  much  water,  but 
more  in  lean  than  in  fat  meat ;  fit  bacon  contains  60  per 
cent. ;  lean  beef,  from  75  to  78  per  cent,  of  water.  As 
the  proportion  of  fat  increases,  the  quantity  of  albuminoids 
or  proteids  decreases :  thus,  lean  beef  may  have  only  2  per 
cent,  of  fat  to  from  20  to  24  per  cent,  of  proteids,  while 
bacon  has  about  24  per  cent,  of  fat  to  15  per  cent,  of 
proteids. 

Of  the  varieties  of  meat  commonly  used,  beef  is  the 
most  nutritious.  Good  beef  should  not  be  too  pale  nor 
too  dark,  should  show  no  blood-clots,  have  almost  no  odor, 
be  elastic  and  not  soggy  to  the  touch,  be  well  marbled 
with  clean,  white  fat,  and  have  compact  flesh.  Dark 
beef  indicates  that  the  animal  was  not  properly  bled,  or 
has  had  some  febrile  disease ;  wet  and  flabby  meat,  that 
it  is  approaching  decomposition.  The  flesh  of  young 
animals  is  more  tender  than  that  of  older  ones,  but  not 
so  digestible,  partly  because  the  young  flesh  cannot  be  so 
thoroughly  masticated  and  the  fibres  so  well  separated. 
Therefore,  veal  is  not  so  digestible  as  beef,  nor  lamb  as 
mutton.  "Young  flesh  is  less  stimulating  and  nutritious 
and  more  gelatinous  than  that  of  the  adult."  (Vaughan.) 
Veal  should  not  be  too  pale,  as  that  indicates  ante-mortem 
bleeding  or  too  young  an  animal.  The  calf  should  be  at 
least  one  month  old  before  the  killing. 

Mutton  is  more  digestible  than  beef,  but  not  so  nutri- 
tious. Its  flavor  is  objectionable  to  some.  Pork  is  an 
economical  food  for  the  poor  man,  as  pigs  of  good  stock 


FISH.  257 

store  up  three  times  as  much  of  the  food  they  eat  as  does 
the  ox.  The  flesh  is  also  easily  preserved  by  drying  or 
smoking,  and  ham  and  bacon  are  exceptions  to  the  rule 
that  dried  meats  are  more  indigestible  than  fresh  ones. 
Again,  pork  fat  furnishes  much  heat  for  cold  weather  by 
its  oxidation  and  combustion  in  the  body.  But  it  must  be 
remembered  that  it  requires  good  digestive  power  to  dis- 
pose of  it,  and  that  much  pork  is  not  to  be  advised  for 
those  of  sedentary  habits ;  also  that  certain  parasites  are 
especially  liable  to  infest  the  tissues  of  the  pig  and  to  be 
transmitted  thence  to  man. 

The  flesh  of  poultry  is  acceptable  to  most  palates,  if  not 
too  old  and  tough.  White  meat  is  more  digestible  than 
the  dark,  but  not  so  nutritious  or  rich  in  flavor,  since  the 
latter  is  more  highly  nitrogenous.  Chicken  broth  is  more 
nutritious  and  more  laxative  than  that  made  from  mutton. 

Fish  is  not  sufficiently  stimulating  to  constitute  the 
chief  flesh  diet  of  a  people,  but  it  furnishes  variety,  and 
on  account  of  its  contained  phosphorus  should  be  used 
largely  by  those  subject  to  neurosal  affections.  White- 
meated  fish  are  more  delicate  in  flavor  and  more  easily 
digested,  but  not  so  stimulating  as  those  of  red  flesh. 
Some  fish  are  poisonous,  either  by  nature  or  from  inhabit- 
ing foul  waters ;  while  any  fish  may  become  so  if  under- 
going decomposition.  Shell-fish  are  particularly  liable 
to  develop  poisonous  ptomains  in  the  process  of  decom- 
position, and,  consequently,  only  such  as  are  absolutely 
fresli  should  be  used. 

Oysters  and  clams  which  have  been  taken  from  a  water 
contaminated  by  sewage  may  also  convey  the  germs  of 
infectious  diseases,  such  as  typhoid  fever;  an  instance  of 
this  having  been  demonstrated  in  the  investigation  of  an 
epidemic  of  the  latter  disease  in  Connecticut,  which  was 
17 


258  FOOD. 

reported  by  Prof.  Conn,  of  AVesleyan  University,  and 
another  in  a  similar  epidemic  at  Atlantic  City,  N.  J,, 
in  1903. 

"The  following  meats  should  not  be  eaten:  1.  The 
flesh  of  all  animals  dead  of  internal  diseases,  or  which 
have  been  killed  while  suffering  from  such  diseases,  or 
animals  killed  by  overdriving.  2.  The  flesh  of  animals 
with  contagious  diseases  that  may  be  transmitted  to  man„ 
3.  The  flesh  of  animals  that  have  been  poisoned.  4.  The 
fle^h  of  animals  with  severe  infectious  diseases,  as  pyaemia, 
etc.  0.  Flesh  that  contains  parasites  that  may  be  trans- 
mitted to  man.     6.  All  putrid  flesh." 

Competent  inspectors  are  appointed  by  governmental 
and  State  authorities  to  examine  the  various  meats  offered 
for  sale  in  large  cities,  and  undoubtedly  do  much  good  in 
preventing  the  sale  of  meat  that  is  unfit  for  use.  Unfor- 
tunately, from  false  ideas  of  economy  in  many  communi- 
ties, the  authorized  inspectors  have  been  too  few  in 
number  to  be  able  to  attend  to  all  the  work  that  should 
be  done  by  them. 

Coplin  and  Bevan  give  the  following  as  diseases  Avhich 
are  to  be  specially  guarded  against :  In  cattle,  epidemic 
pleuro-pneumonia,  foot-and-mouth  disease,  contagious  ty- 
phus, antlirax,  tuberculosis,  actinomycosis,  Texas  fever, 
dropsical  affections,  and  indigestion.  In  sheep,  braxy, 
variola  ovina,  black  quarter,  phthisis,  fluke  disease,  and 
gid.  In  swine,  anthrax,  hog  cholera,  measles,  and  trichin- 
iasis.^  It  should  also  be  remembered  that  the  intestinal 
])arasites,  such  as  tape-worms  and  round-worms,  often,  if 
not  usually,  gain  entrance  into  the  system  through  the 
ingestion  of  meat  containing  them  in  their  embryonal  or 
larval  stages. 

1  Gerlach.        '■'  Manual  of  Practical  Hygiene,  1st  edition,  p.  132  et  seq. 


THE  COOKING   OF  MEAT.  259 

Therefore,  in  cooking  meat,  every  part  should  be  heated 
to  at  least  160°  F.  sufficiently  long  to  destroy  any  disease 
germs  or  parasites  it  may  contain,  as  very  rare  meat  may 
still  harbor  these  organisms  in  a  living  state.  Tubercu- 
losis, for  instance,  may  be  incurred  by  eating  flesh  imper- 
fectly cooked,  since  its  germs  are  quite  resistant ;  though  it 
must  be  said  that  this  disease  is  not  so  likely  to  affect  the 
muscular  tissues  of  an  animal  as  are  others  of  the  maladies 
mentioned.  The  development  of  ptomai'ns  in  flesh  may 
also  make  it  quite  poisonous,  and  this  is  especially  likely 
to  take  place  in  meats  that  have  been  kept  for  a  long  time 
after  killing  or  in  those  preserved  in  cans  or  other  pack- 
ages that  have  been  imperfectly  heated  or  sealed. 

Meat  is  also  cooked  to  improve  it  in  appearance  and  to 
make  it  more  agreeable  to  the  palate  and  to  aid  digestion. 
As  already  stated,  the  effect  of  cooking  upon  muscle-tissue 
is  "  to  loosen  the  bundles  of  fibrillse  from  each  other  so  that 
they  are  readily  torn  asunder  or  crushed  by  the  teeth." 
Perfectly  cooked  flesh  is  more  savory  than  that  which  is 
either  underdone  or  overdone.  Meat  cooked  before  rigor 
mortis  sets  in  may  be  tender ;  cooked  during  the  ingor,  it 
is  tough  and  is  masticated  with  difficulty ;  after  the  rigor, 
it  is  more  likely  to  be  tender  when  cooked  than  at  any 
previous  time. 

In  cooking  meat,  the  ultimate  condition  in  which  we 
wish  it  to  be  should  always  be  kept  in  mind,  and  pains 
should  also  be  taken  not  to  overcook  or  use  too  high  a  tem- 
perature. The  processes  pursued  in  making  a  palatable 
soup  or  broth,  and  in  cooking  meat  so  that  it  may  retain 
all  its  juices,  salts,  and  flavors,  are  radically  different.  In 
the  first  case,  it  is  desired  to  extract  as  much  of  the  soluble 
constituents  of  the  flesh  as  possible,  and  to  do  this  the  meat 
should  be  cut  into  small  pieces  and  allowed  to  remain  for 


260  FOOD. 

a  time  in  cold  water,  this  afterward  being  very  gradually 
raised  to  a  temperature  of  about  160°  F.  In  this  way 
the  juices  exude  and  the  salts  and  soluble  parts  of  the 
meat  are  dissolved  before  the  pores  are  closed  by  the 
coagulation  of  the  albumin.  On  the  other  hand,  if  it  is 
desired  to  retain  the  juices  and  savor  in  the  meat,  the  piece 
should  be  as  large  as  possible  that  tlie  surface  exposed  will 
be  small  in  proportion  to  the  volume.  The  meat  is  to  be 
first  subjected  to  a  temperature  as  high  as  possible  that  the 
surface  may  be  cooked  at  once  and  the  albumin  coagulated, 
the  juices  being  thus  prevented  from  escaping  by  the  seal- 
ing of  the  pores.  In  boiling,  this  end  is  attained  by 
plunging  the  meat  at  once  into  boiling  Avater ;  in  roasting, 
by  having  the  fire  or  oven  very  hot.  After  this  first  heat- 
ing it  is  best  to  lessen  the  degree  of  heat  somewhat,  that  the 
subsequent  cooking  of  the  interior  may  go  on  more  slowly 
and  the  temperature  within  may  not  rise  above  the  coagu- 
lating-point  and  make  the  filsres  hard  and  stringy.  Meat 
cooked  in  this  way  should  be  tender,  juicy,  and  rich  in 
flavor.  Broiling  or  grilling  is,  of  course,  but  a  modified 
roasting. 

Soups  and  broths  made  of  meat-juices  alone  and  with- 
out the  addition  of  other  substances  are  stimulating  rather 
than  nutritious,  as  they  contain  little  albumin,  carbo- 
hydrates, or  fat.  However,  if  certain  vegetables  be  added 
to  tlie  soup,  the  latter  will  gain  sufficient  of  these  food- 
principles  and  be  highly  nutritious,  and  such  vegetable 
soups  are  of  great  value  in  all  schemes  of  cconomi(!  cook- 
ing. Bones  are  also  of  value  on  account  of  the  salts, 
gelatin,  and  other  soluble  organic  matter  which  they  con- 
tain, and  used  with  vegetables  they  make  especially  nutri- 
tious and  easily  digested  soups. 

The  meat  from  which  soup  has  been  made,  on  the  other 
hand,  is  not  all  that  is  desirable,  for  tliough  it  still  con- 


FRYING:   BEEF-TEA.  261 

tains  albumin  and  fat,  it  has  lost  its  salts  and  savoriness 
and  is  unpalatable,  and  therefore  not  easily  digested.  It 
needs  something — a  sauce  or  condiment,  or  preferably  a 
meat-extract,  for  meat-extracts  are  nothing  but  thin  soups 
evaporated  to  dryness  or  condensed.  Or,  if  both  soup 
and  the  meat  be  taken  at  the  same  meal,  the  things 
lacking  in  each  are  supplied  by  the  other,  and  the  needs 
of  digestion  and  nutrition  are  supplied. 

Frying  meat,  as  it  is  commonly  practised,  should  not 
be  tolerated,  as  it  renders  the  albumin  of  the  flesh  ex- 
tremely tough,  besides  soaking  it  with  fat  or  grease  and 
thus  greatly  increasing  the  difficulty  of  its  digestion. 
But  frying  by  total  immersion  in  boiling  fat  is  an  excel- 
lent way  of  cooking  meats  containing  much  water,  and 
especially  fish,  for  the  boiling-point  of  fat  or  oil  is  very 
high  and  the  meat  is  instantly  cooked  on  the  outside, 
while  the  water  in  the  interior,  being  converted  into 
steam,  prevents  the  ingress  of  fat  by  its  expansion,  cooks 
the  albumin,  and  leaves  the  flesh  in  a  light,  flaky  condi- 
tion. But  the  fat  must  be  boiling  hot  when  the  meat  is 
immersed,  and  the  latter  should  not  be  allowed  to  remain 
in  the  former  longer  than  just  suffices  for  perfect  cooking. 

Beef-tea  as  ordinarily  made  is  only  a  thin  extract  of 
beef,  the  stimulating  properties  of  which  will  be  consid- 
ered hereafter.  To  make  a  beef-tea  containing  any  con- 
siderable amount  of  nutriment,  the  meat  from  which  the 
juices  have  been  extracted  should  be  dried,  pounded 
fine,  and  all  fibrous  and  tendinous  portions  removed. 
This  pounded  beef  should  then  be  added  to  the  liquid 
extract,  as  then  only  is  it  really  a  food.  Moreover,  the 
mixture  should  always  be  seasoned,  even  for  the  sick, 
that  it  may  be  thoroughly  acceptable  to  both  palate  and 
stomach.  In  making  the  extract,  remember  that  the 
meat  should  be  cut  into  very  small  pieces  and  added  to 


262  FOOD. 

cold  water  in  about  tlie  proportion  of  one  pound  of  lean 
meat  to  one  pint  of  water,  and  that  the  whole  should  be 
brought  to  the  boiling-point  very  slowly. 

Cereals. — The  cereals  forna  one  of  the  most  valuable 
kinds  of  food.  All  but  rice  contain  considerable  proteid 
matter — from  10  to  20  per  cent. — ^beside  carbohydrates, 
which  predominate,  some  fat,  and  a  goodly  proportion  of 
phosphates.  Rice  has  only  5  per  cent,  of  proteids  to  75 
per  cent,  of  starch,  but  it  is  easily  digested,  and  is  there- 
fore a  valuable  food  for  the  young  and  the  sick ;  it  is  also 
well  fitted  as  a  chief  food  for  dwellers  in  hot  climates  on 
account  of  its  low  heat-production. 

Wheat  is  the  most  nutritious  cereal,  and  bread  made 
from  it  is  aptly  called  "  the  staff  of  life,"  since  it  is  a 
food  which,  with  the  addition  of  a  little  extra  fat  and 
albumin,  furnishes  the  essentials  in  proper  proportion  for 
the  support  of  life.  Barley  closely  resembles  wheat  in 
composition,  and  rye  also  is  rich  in  nutriment,  though 
perhaps  a  little  more  difficult  of  digestion  than  wheat. 
Oats  are  valuable  on  account  of  the  large  amount  of  fat 
they  contain — over  5  per  cent. — beside  a  full  share  of 
proteids,  starch,  and  salts.  But  ordinary  oat-meal  needs 
vigorous  digestive  functions,  and  where  the  latter  are 
lacking  it  is  often  productive  of  intestinal  disturbance 
and  irritation.  Corn  or  maize,  though  not  a  true  cereal, 
furnishes  a  valuable  food  with  considerable  fat;  it  also 
contains  a  vegetable  fibrin.  The  proteid  constituents  of 
the  cereals  are  vegetable  albumin,  casein,  and  gluten,  the 
last  of  tlu'se  being  most  abundant  in  wheat  and  perhaps 
of  the  highest  food-value. 

Grinding  breaks  up  the  grain  and  the  starch  granules 
of  the  cereals,  aids  in  s('j)arating  indigestible  parts,  and 
renders  the  starch  much  more  suitable  for  cooking. 
Wheat  flour  ground  by  the  old  method  should  be  soft  and 


CEREALS:  BREAD.  263 

smooth,  but  that  made  by  the  new  roller-process  is  more 
apt  to  be  slightly  granular.  It  should  not  be  too  white, 
as  that  indicates  a  lack  of  the  proper  proportion  of  gluten, 
and  should  contain  everything  but  the  outer  husk  of  the 
grain.  The  inner  coats  should  be  retained  in  the  flour, 
as  they  hold  a  considerable  part  of  the  gluten  and  practi- 
cally all  of  the  grain  salts.  Corn-meal  should  be  dry  and 
powdery,  or  at  least  not  too  granular.  Flour  of  any  kind 
should  be  kept  well  covered  in  a  dry  place,  and  should 
contain  no  living  organisms  nor  any  adulterants. 

Bread  is  practically  made  of  flour,  water,  and  salt, 
though  sugar,  milk,  etc.,  may  be  added  to  improve  the 
flavor.  As  flour  and  water  alone  make  a  tough  and  in- 
digestible mass,  bread  is  leavened  to  make  it  easier  of 
mastication  and  digestion,  and  for  this  purpose  either 
yeast,  baking-powder,  or  aeration  is  employed.  Yeast  at 
the  proper  temperature  rapidly  converts  some  of  the  starch 
or  sugar  into  carbon  dioxide  and  alcohol,  the  former  of 
which  in  escaping  makes  the  dough  porous  and  light,  the 
walls  of  the  cavities  it  produces  being  kept  from  collaps- 
ing by  the  tenacity  of  the  gluten  until  the  heat  fixes 
them  permanently.  As  the  heat  of  baking  dissipates  both 
the  gas  and  alcohol,  from  10  to  12  per  cent,  of  the  weight 
of  the  flour  used  is  lost  by  this  method.  Moreover,  if  the 
fermentation  goes  beyond  a  certain  point,  lactic  and  acetic 
acids  are  formed  and  the  bread  becomes  "  sour."  Con- 
sequently, it  has  been  advised  that  the  yeast  method  be 
discarded,  and  that  the  leavening  be  done  by  means  of 
baking-powders  or  aeration.  Carbon  dioxide  is  evolved 
from  the  baking-powders  upon  the  application  of  heat  and 
moisture,  and  the  bread  is  made  light  by  the  gas,  with  no 
loss  of  food-substance,  and,  if  the  powders  are  pure,  with 
nothing  harmful  added  to  the  bread.  There  should  be 
no   alum   or   other    adulterants    in    baking-powders   nor 


264  FOOD. 

ill  the  flour  itself.  Alum  unites  with  the  phosphates 
of  the  flour,  rendering  them  insoluble  and  preventing 
their  absorption  from  the  alimentary  tract.  Bread  may 
also  be  leavened  on  a  large  scale  by  forcing  air  or 
carbon  dioxide  under  high  pressure  into  the  dough,  or 
by  mixing  the  flour  with  cold  water  heavily  charged 
with  the  latter  gas.  In  this  method,  also,  there  can  be 
no  loss  of  food-material  nor  any  detriment  to  the  bread, 
provided  cleanly  precautions  are  observed. 

Good  wheat  bread  should  be  almost  white,  light,  sweet, 
spongy,  and  with  a  crust  easily  broken  and  equal  in  bulk 
to  about  one-quarter  of  the  loaf.  As  considerable  of  the 
starch  has  been  converted  into  dextrine  in  the  crust,  the 
latter  is  more  easily  digested  than  the  interior  of  the  loaf. 
Fresh  bread  is  not  nearly  so  digestible  as  that  which  is 
a  day  or  two  old.  As  stated,  bread  needs  only  a  little 
added  fat  and  albumin  to  make  it  a  perfect  food,  the 
former  of  which  at  least  is  almost  if  not  quite  sufficiently 
supplied  in  the  butter  which  is  commonly  used  upon  it. 

Vegetables. — The  vegetables  in  common  use  are  valu- 
able articles  of  food  in  that  they  give  us  the  larger 
portion  of  carbohydrates  and  also  furnish  an  agreeable 
variety  from  day  to  day.  In  the  fresh  state  they  contain 
considerable  water — from  75  to  90  or  95  per  cent. — the 
residue  being  mainly  one  or  another  of  the  carbohydrates. 
Potatoes  exemplify  this  well,  since  they  contain  but  little 
proteids  and  fat,  and  practically  all  of  their  solid  matter 
is  starch.  On  account  of  their  customary  cheapness  and 
ease  of  growth  and  storage  they  are  usually  considered 
to  be  a  valuable  article  of  food  for  the  poor  man,  but 
it  should  not  be  forgotten  that  other  foods  which  are 
apparently  more  expensive  may  at  times  be  actually 
cheaper  than  potatoes,  both  on  account  of  containing 
those  principles  which  the  latter  lack  and  because  they 


VEGETABLES.  265 

require  less  expenditure  of  digestive  energy.  (See  chart, 
page  269.)  Beets  contain  much  sugar  and  are  uutritiouSj 
palatable,  and  easily  digested.  Onions  have  considerable 
sulphur,  and  should  be  used  freely  when  its  need  is  indi- 
cated. Cabbage,  cress,  and  other  greens  are  especially 
valuable  for  the  organic  salts  which  they  contain,  and 
because  they  serve  so  well  as  relishes.  Spinach  is  said  to 
contain  more  assimilable  iron  than  any  other  article  of 
food  commonly  used.  Celery  and  lettuce  are  nerve  seda- 
tives, and  asparagus  acts  as  a  diuretic  and  is  thought  to  be 
of  special  benefit  to  the  kidneys. 

A  caution  should  be  introduced  here  concerning  the 
use  of  raw  vegetables  which  may  carry  from  the  soil  the 
germs  of  certain  infectious  disease  and  which  latter  have 
been  derived  from  the  fertilizers  used  or  from  other 
sources.  There  can  be  no  doubt  that  these  have  been  the 
cause  of  infection  in  certain  cases,  as  of  typhoid  fever, 
and  Metchnikoff  has  pointed  out  that  while  such  germs 
are  probably  destroyed  by  the  normal  bacteria  and  reac- 
tions of  the  digestive  tract,  an  abnormal  condition  of  the 
latter  may  permit  their  introduction  and  the  development 
of  their  specific  maladies. 

The  seeds  of  the  leguminous  group  of  plants,  such  as 
peas,  beans,  lentils,  etc.,  contain  from  22  to  25  per  cent, 
of  proteid  matter  in  the  form  of  vegetable  casein,  and 
almost  50  per  cent,  of  starch.  It  is  on  account  of  this 
abundance  of  food-matter  that  they  make  such  a  valuable 
addition  to  soups  and  the  like,  and  for  the  same  reason 
they  should  also  be  used  in  any  dietary  where  economy 
of  expense  is  a  factor.  Green  peas  and  beans  are  much 
more  digestible  than  those  that  have  ripened  and  dried, 
though,  of  course,  they  do  not  yield  so  much  nutriment, 
weight  for  weight,  as  the  latter. 

All  vegetables  should  be  so  cooked  as  to  retain  their 


266  FOOD. 

salts,  or  else  the  M^ater  in  which  they  are  cooked  and 
which  contains  these  salts  should  be  used  in  making  soup 
or  broth,  to  be  served  at  the  same  meal  with  the  vege- 
tables. This  is  especially  advisable  with  regard  to  pota- 
toes and  sweet  potatoes,  as  their  soluble  salts  have  much 
to  do  with  their  digestiljility.  It  is  for  this  reason  that 
a  properly  roasted  potato  is  always  better  than  a  boiled 
one,  and  that  steamed  vegetables  are  both  more  palatable 
and  more  digestible  than  those  which  have  been  cooked 
under  water.  In  fact,  Mattieu  Williams  has  even  sug- 
gested that  possibly  one  reason  why  gout  is  so  prevalent 
among  Englishmen  is  because  they  habitually  eat  boiled 
vegetables  and  throw  away  the  water  in  which  these  have 
been  cooked.  The  salts  not  only  help  in  the  digestion  of 
the  starches,  but  they  furnish  bases  to  unite  with  and 
render  soluble  the  irritating  acids  that  produce  the  gouty 
symptoms.  It  should  also  be  remembered  that  the  dried 
legumes  should  always  be  softened  by  soaking  in  water 
before  cooking,  and  that  they  as  well  as  other  vegetables 
should  be  cooked,  whenever  possible,  in  soft  water. 

Prepared  starches,  such  as  arrow-root,  tapioca,  sago, 
etc.,  are  easily  digestible,  and  therefore  useful  especially  in 
the  preparation  of  food  for  the  young  and  the  sick. 

Fruits  are  especially  valuable  on  account  of  their 
flavor,  acceptability  to  the  palate,  benefit  to  the  diges- 
tion, and  for  their  laxative  action.  Ripe  fruits  may  be 
eaten  freely  :  in  most  cases  preferably  early  in  the  day. 
Fresh  fruits  are  usually  better  than  those  dried  or  other- 
wise preserved  ;  but  where  the  former  cannot  be  had,  the 
latter  should  be  used  freely,  and  all  sliould  be  used 
throughout  the  year  whenever  possible.  Green  fruit,  or 
that  which  has  begun  to  decay,  should  not  be  eaten,  for 
obvious  reasons. 


ADULTERANTS  AND   PRESERVATIVES.  267 

Nuts  are  nutritious  on  account  of  the  high  percentage 
of  fat  that  most  of  them  contain,  but  are  difficult  of  diges- 
tion unless  thoroughly  masticated.  Recently  pastes  made 
from  various  nuts  have  been  placed  on  the  market,  and 
are  to  be  considered  as  an  agreeable  addition  to  our 
dietaries. 

Adulterants  and  Preservatives. — Much  might  be 
written  concerning  the  adulteration  and  sophistication 
of  food-stuffs  and  of  the  addition  of  more  or  less  harmful 
preser^'atives  to  food  of  a  perishable  nature.  That  the 
first  is  carried  on  to  an  enormous  extent  seems  certain. 
The  remedy  appears  to  be  in  the  passage  and  enforcement 
of  stringent  laws  and  the  maintenance  of  frequent  and 
rigid  inspection  by  both  State  and  governmental  authori- 
ties, in  the  dissemination  of  information  as  to  the  adultera- 
tions practised  and  the  means  of  detecting  them,  and  in  the 
utmost  publicity  and  exposure  in  the  case  of  transgressors, 
all  of  which,  it  is  to  be  hoped,  will  now  be  effected  by  the 
provisions  of  the  new  Pure  Food  and  Drugs  Act  and 
the  means  employed  for  its  enforcement. 

This  law,  which  became  effective  on  January  ],  1907, 
jirovides  "  That  for  the  purposes  of  the  act,  an  article 
siiall  be  deemed  to  be  adulterated  in  the  case  of  food  : 
First.  If  any  substance  has  been  mixed  and  packed  Mith 
it  so  as  to  reduce,  or  lower,  or  injuriously  affect  its  quality 
or  strength.  Second.  If  any  substance  has  been  substi- 
tuted wholly  or  in  part  for  the  article.  Third.  If  any 
valuable  constituent  of  the  article  has  been  wholly  or  in 
part  abstracted.  Fourth.  If  it  be  mixed,  colored,  pow- 
dered, coated,  or  stained  in  a  manner  whereby  damage  or 
inferiority  is  concealed.  Fifth.  If  it  contain  any  added 
poisonous  or  other  added  deleterious  ingredient  which  may 
render  such  article  injurious  to  liealth.  Sixth.  If  it  consists 
in  Avhole  or  in  part  of  a   filthy,  decomposed,  or  putrid 


268  FOOD. 

animal  or  vegetable  substance  or  any  portion  of  an  animal 
unfit  for  food,  Avliether  manufactured  or  not,  or  if  it  is  the 
product  of  a  diseased  animal,  or  one  that  has  died  other- 
wise than  by  slaughter." 

In  the  opinions  of  the  officials  of  the  Department  of  Agri- 
culture, to  whom  the  administration  of  the  law  is  entrusted, 
several  thousand  chemists,  inspectors,  and  collectors  will 
be  needed  to  carry  out  its  provisions,  necessitating  an 
annual  expenditure  by  the  Government  of  about  $750,000. 

As  to  the  use  of  preservatives,  the  very  extensive  sale, 
heretofore,  of  these  in  localities  where  they  would  be  most 
likely  to  be  added  to  food  indicates  their  employment,  as 
does  their  continual  discovery  by  direct  analysis.  In  Bir- 
mingham, England,  such  preservatives  were  found  in  20 
per  cent,  of  2300  samples  of  food  examined,  and  boric  acid 
in  5  per  cent,  of  1360  samples  of  milk.  Such  substances  as 
boric  acid,  salicylic  acid,  and  formaldehyde  are  commonly 
used,  though  it  is  frequently  stated  that  more  dangerous 
ones,  such  as  hydrofluoric  acid,  are  occasionally  employed. 
And  though  it  should  in  fairness  be  stated  that  it  is  pos- 
sible that,  if  only  the  minimum  of  such  substances  as  boric 
acid  and  formaldehyde  necessary  to  prevent  putrefactive 
or  fermentative  changes  in  food  be  used,  no  harm  to  the 
liiiiuan  economy  will  result,^  yet  it  is  undoubtedly  wiser 
to  oondcmn  tlio  practice  of  adding  chemical  preservatives 
of  any  kind  to  food.     There  are  two  reasons   for  this  : 

1  Ridcal  and  Fullerton  (Public  Health,  May,  1899)  arrive  at  the  fol- 
lowing conclusions:  1.  Boric  acid  (1  to  2000)  and  formaldehyde  (1  to 
50,000)  arc  effective  preservatives  for  milk  for  twenty-four  hours.  2. 
These  quantities  have  no  appreciable  effect  upon  the  di<;cstion.  3.  These 
<|uantities  have  no  appreciable  effect  upon  the  digestibility  of  foods  pre- 
pared with  them.  4.  Formaldehyde  in  the  proportion  given  above,  so  far 
as  their  invc'Sf igations  have  extended,  does  not  appear  to  have  any  in- 
jurious action  upon  animal  tissues  or  nutrition. 


ADULTERANTS  AND   PRESERVATIVES. 


269 


1.  There  is  no  surety  and  very  little  probability  that  the 
minimum  quantity  of  preservative  consistent  with  safety  to 
health  will  not  be  exceeded  in  most  eases  through  careless- 
ness or  recklessness.  2.  That  foods  that  apparently  require 
such  preservatives  should  be  supplied  to  the  consumer 
before  the  deterioration  in  them  has  begun,  or  else  they 
should  be  sterilized  by  the  more  costly  but  safer  employ- 
ment of  heat. 

The    following   diagram   may  be  of  service   in  deter- 
mining the  value  of  certain  food-stuifs  : 


Fig.  51. 


CHAPTER    VII. 

STIMULANTS  AND  BEVERAGES. 

The  essential  function  and  property  of  stimulants  is  to 
liberate  some  of  the  latent  force  of  the  body,  and  they  are 
of  use  and  value  in  sudden  emergencies,  to  tide  the  system 
over  important  crises,  to  hasten  a  tardy  convalescence, 
or  perchance  to  whip  up  a  flagging  digestion  so  that  it 
may  the  better  prepare  food  for  the  repair  of  waste  or 
the  supplying  of  body-fuel.  Those  stimulants,  excluding 
drugs,  with  which  we  are  most  concerned  are  of  three 
classes,  viz.,  nitrogenized  vegetable  stimulants,  such  as 
tea  and  coffee ;  nitrogenized  animal  stimulants,  as  beef- 
tea  and  meat-extracts  ;  and  alcohol.  All  these  are  "  force- 
liberators,"  and  though  alcohol  may  sometimes  act  the 
part,  in  more  moderate  measure,  of  a  "  force-producer," 
it  is  well  to  remember  that  they  give  scarcely  anything 
at  all  to  renew  or  replace  tlie  energy  which  they  set  free. 
This  being  so,  care  should  always  be  taken  that  some 
food  be  supplied  during  or  shortly  after  the  stimulation 
j)ro(luced  by  the  agents  in  question,  in  order  that  the 
body  may  have  a  new  store  of  force  to  replace  that  which 
has  ])cv.n  liberated.  Especially  is  this  necessary  in  cases 
of  sickness ;  and  as  the  soluble  carbohydrates  furnish  fuel 
and  consequent  heat  and  energy  to  carry  on  the  vital  pro- 
cesses, these  even  more  than  other  kinds  of  food  are  to  be 
supplied,  and  will  generally  be  well  received  and  utilized 
by  patients  or  others  in  need  of  stimulation.  Again,  just 
270 


TEA  AND   COFFEE.  271 

as  we  must  not  depend  on  stimulants  alone  to  the  exclu- 
sion of  food,  so  also  must  we  take  care  not  to  continue 
their  use  any  longer  than  is  necessary  to  attain  our  object, 
and  likewise  must  not  overstimulate  or  carry  the  action 
so  far  that  the  body  is  left  poorer  and  weaker  in  force 
than  before  the  use  of  the  stimulants  began. 

For  example,  beef-tea  constantly  stimulates  the  vital 
and  nervous  functions  to  greater  activity,  this  requiring 
that  either  tissue  or  food  be  oxidized  to  produce  the  neces- 
sary energy.  The  stimulating  factors  in  ordinary  beef-tea 
are  the  meat-extractives,  such  as  kreatin  and  kreatinine, 
which  are  products  of  the  wear  and  tear  of  life,  inter- 
mediate between  living,  active  tissue  and  the  final  excre- 
tory matters,  such  as  urea  and  uric  acid  ;  hence  they  can 
have  little,  if  any,  real  food-value.  Beside  these  the  beef- 
tea  contains  only  the  salts  of  the  meat,  which,  though  valu- 
able, are  not  force-producers.  Therefore,  unless  food  be 
otherwise  supplied,  the  body-tissue  must  be  consumed, 
and  the  result  must  eventually  be  in  the  end  disastrous ; 
and  yet  this  is  what  occurs  to  many  patients  through  the 
mistaken  idea  that  beef-tea  is  both  nourishing  and  stimu- 
lating. When  "  whole  beef-tea "  (the  recipe  for  which 
is  given  on  page  251)  is  used,  these  remarks  do  not 
apply,  since  it  contains  some  true  food,  though  even  here 
soluble  or  readily  digestible  carbohydrates  may  wisely  be 
added. 

The  active  principles  of  the  nitrogenized  vegetable 
stimulants  resemble  very  closely  in  chemical  composition 
not  only  the  meat-extractives,  but  also  those  drugs,  like 
strychnine,  which  are  used  in  medicine  as  tonics  and 
cerebrospinal  stimulants,  and  they  act  physiologically  in 
a  similar  though  milder  manner. 

As  beverages,  tea,  coffee,  and  cocoa  supply  fluid  for  the 


272  STIMULANTS  AND  BEVERAGES. 

system  and  that  stimulation  of  the  assimilative  functions 
that  causes  a  sense  of  comfort  after  their  use,  cocoa  and 
chocolate  having  also  the  advantage  of  supplying  some 
food.  But  these  beverages  may  all  be  abused  in  their  use 
as  readily  as  may  beef-tea  or  alcohol,  and  "  tea-drunkards  " 
and  "  coifee-drunkards  "  are  not  uncommon  in  hospitals 
and  in  private  life.  The  teacup  is  not  always  the  one 
that  "  cheers  but  does  not  inebriate."  Women  especially 
who  drink  much  tea  are  apt  to  be  nervous  and  dyspeptic, 
to  have  the  "  tea-drinker's  heart,"  and  to  suffer  from 
headaches  and  neuralgias.  They  depend  upon  tea  to  take 
the  place  of  nutriment,  and  soon  use  up  what  little  store 
of  force  they  may  have  had,  since  they  fail  to  replenish  it 
with  fuel-food.  Men  are  more  addicted  to  the  use  and 
abuse  of  coffee,  and  often  manifest  symptoms  directly 
traceable  to  such  intemperance.  While  caffeine  increases 
heart  action,  and  may  be  used  to  advantage  in  cases  of 
cardiac  debility,  for  the  same  reason  it  should  be  taken 
with  caution  and  in  moderation  where  the  cardiac 
action  is  already  too  vigorous.  Vogel  has  advised  the 
use  of  strong  coffee  with  sugar  and  cream  as  a  tonic 
and  food  in  debility  accompanying  the  acute  diseases 
of  children. 

It  is  interesting  to  note  that  among  all  nervous,  ener- 
getic people  the  use  of  some  one  or  other  of  these  stimu- 
lant beverages  is  common,  and  that  "total  abstainers" 
from  alcoliol  seem  instinctively  to  resort  to  tea  or  coffee. 
And  while  it  is  probably  theoretically  true  that  the 
healthy  person  would  better  abstain  entirely  from  the  use 
of  stimulants,  except  in  emergencies  or  at  rare  intervals, 
yet  tlie  almost  imiversal  desire  for  and  use  of  tliem  prol)- 
ably  indicate  that  under  our  present  high  tension  of 
living  there  is  a  real  physiological  demand  and  need  for 


ALCOHOL.  273 

them  that  perhaps  should  be  satisfied  in  a  measure,  but 
with  moderation  and  judgment. 

Alcohol. — Liebig  says  that  "  alcohol  stands  only  second 
to  fat  as  a  respiratory  material/'  but  adds  that  "  the  same 
effect  could  be  produced  in  the  body  by  means  of  sac- 
charine and  farinaceous  articles  of  food  at  one-fourth  or 
one-fifth  the  cost."  Fothergill  also  holds  "  that  the  chief 
portion  of  the  alcohol  ingested  undergoes  consumption  in 
the  body,"  but  insists  that  "  the  question  of  '  alcohol  as  a 
food'  can  never  be  separated  or  divorced  from  that  of 
'  alcohol  as  a  stimulant '  or  as  a  force-liberator." 

Much  undue  importance  has  recently  been  given  to 
some  scientific  investigations  that  served  to  establish  the 
fact  that  alcohol  can  be  and  often  is  almost  completely 
oxidized  in  the  body,  and  that  it  produces  therein  jjrac- 
tically  the  same  number  of  heat-units  as  when  it  is  con- 
sumed outside.  But  the  inference  that  it  can  therefore 
be  substituted  for  and  used  with  impunity  in  place  of  the 
usual  carbonaceous  foods  is  not  justifiable,  because  the 
powerful  physiological  and  ultimate  pathological  effect 
of  the  alcohol  upon  the  higher  nerve-centres  and  active 
tissues  is  ignored,  because  of  the  liberation  of  the  body's 
latent  force  in  excess  of  the  energy  which  the  alcohol  sup- 
plies, and  because  even  the  above-mentioned  investigations 
and  experiments  went  to  show  that  there  was  an  actual 
detriment  to  the  nitrogen-bearing  tissues  of  the  body  dur- 
ing its  use. 

Again,  Liebig  writes  that  "  the  use  of  spirits  is  not  the 
cause  but  the  effect  of  poverty.  It  is  the  exception  to 
the  rule  when  the  well-fed  man  becomes  a  spirit-drinker. 
On  the  other  hand,  when  the  laborer  earns  by  his  work 
less  than  is  required  to  provide  the  amount  of  food  which 
is  indispensable  in  order  to  restore  fully  his  working 
18 


274  STIMULANTS  AND  BEVERAGES. 

power,  an  unyielding,  inexorable  law  or  necessity  compels 
him  to  have  recourse  to  spirits.  He  must  work ;  but  in 
consequence  of  insufficient  food  a  certain  portion  of  his 
working  power  is  daily  wasting.  Spirits,  by  their  action 
on  the  nerves,  enable  him  to  make  up  the  deficient  power 
at  the  expense  of  his  body ;  to  consume  to-day  that  quan- 
tity which  naturally  ought  to  have  been  emplcyed  a  day 
later."  This  may  also  be  the  case  where  there  is  an 
abundance  of  food,  but  where  it  is  improperly  chosen 
for  the  needs  of  the  individual  or  ruined  by  bad  cook- 
ing. Education  in  the  principles  of  the  scientific  and 
economical  selection  of  food  and  its  preparation  may 
thus  become  a  means  of  preventing  those  diseases  that 
depend  on  or  are  aggravated  by  insufficient  or  improper 
food  and  consequent  alcoholic  excesses.  The  effect  of 
alcohol  upon  the  weak  and  savage  races  is  much  more 
marked  and  disastrous  than  upon  the  civilized  and  strong; 
so  it  harms  the  health  of  the  underfed  and  overworked 
much  more  than  it  does  that  of  the  well-fed  man  of  means 
and  leisure,  and  affects  women  and  children  more  than 
adult  men.  This  latter  point  is  to  be  remembered  in 
practice. 

Remember  also  that,  wliile  alcohol  is  partially  a  respira- 
tory stimulant,  it  is  a  forec-libcrator  and  consumes  the 
body-store,  and  unless  given  with  other  readily  oxidizable 
fodd  the  risk  is  run  of  putting  a  patient  "in  a  grave 
never  dug  by  Nature,"  especially  where  there  is  already 
danger  of  the  patient  sinking  from  exhaustion.  But  it  is 
just  in  these  cases,  when  given  with  other  food,  that  we 
find  alcohol  a  valuable  thera])eutic  agent.  Give  it  with 
foods  that  produce  heat  and  force — /.  e.,  some  form  of 
the  soluble  carbohydrates,  as  maltose,  malt-extracts,  milk, 
milk-whey,  or  even  sugar.    Where  the  assimilative  powers 


EFFECTS   OF  ALCOHOL.  275 

are  weak  it  may  be  advantageous  or  necessary  partially  or 
wholly  to  predigest  these  foods ;  but  above  all,  remember 
to  replace  what  alcohol  takes  from  the  body,  or  physio- 
logical bankruptcy  will  ensue.  Note  also  that,  though 
alcohol  may  be  in  one  sense  a  food,  it  is  a  very  costly  one, 
and  that  intoxication  must  occur  long  before  a  man  could 
get  the  equivalent  of  a  full  meal. 

Alcohol  is  to  be  used  in  sickness  practically  to  sustain 
the  vital  powers,  to  meet  emergencies,  and  to  lift  the 
patient  over  obstructions  in  the  road  to  health ;  and  such 
use  requires  a  thorough  knowledge  of  its  action  coupled 
with  the  highest  judgment. 

In  malt  liquors  there  is  usually  considerable  maltose, 
thus  combining  with  the  alcohol  a  soluble  carbohydrate 
of  the  highest  value,  and  these  brewed  ales,  etc.,  may 
often  be  used  with  benefit  as  tonics,  especially  where  con- 
valescence is  protracted.  The  stronger  distilled  liquors 
are  diffusible  cardiac  stimulants,  and  are  especially  valu- 
able in  emergencies,  but  the  continued  use  of  them  must 
only  be  advised  with  great  caution.  Fothergill  gives  two 
excellent  rules  for  the  use  of  alcohol  by  the  healthy : 
"  First,  never  have  alcohol  in  the  brain  when  it  has  work 
to  do ;  second,  a  little  alcohol  betwixt  a  man  and  past 
trouble  is  permissible  ;  but  it  is  not  well  to  put  a  little 
alcohol  in  front  of  a  coming  trouble."  Murchison,  in  his 
work  on  Fevers,  lays  down  these  rules  for  practice,  which 
it  would  be  well  for  all  to  adopt :  "  A¥hat  are  the  con- 
ditions of  the  animal  economy  in  which  alcohol  may  be 
of  positive  use?  That  there  are  such  conditions,  I  believe 
cannot  be  denied  by  any  one  who  has  honestly  studied  the 
subject ;  but  they  are  not  the  conditions  of  perfect  health. 
It  is  especially  when  the  circulation  is  weak  or  sluggish 
that  a  daily  allowance  of  alcohol  may  do  good.    Thus  :  1. 


276  STIMULANTS  AND  BEVERAGES. 

Alcohol  is  useful  iii  the  course  of  most  acute  diseases 
when  the  organs  of  circulation  begin  to  fail,  as  they  are 
apt  to  do.  A  moderate  quantity  usually  suf&ces.  The 
large  quantity  still  sometimes  administered  may  do  harm 
by  inducing  congestion  of  internal  organs.  2.  In  con- 
valescence from  acute  diseases  or  from  weakening  ail- 
ments, when  the  circulation  remains  feeble  and  the  tem- 
perature is  often  subnormal,  alcohol  is  useful  in  promoting 
the  circulation  and  assisting  the  digestion.  3.  In  persons 
of  advanced  life  the  circulation  is  also  often  feeble,  and 
a  moderate  allowance  of  alcohol  often  appears  to  be  bene- 
ficial. All  other  conditions  of  the  system  marked  by 
w^eakness  of  the  muscular  wall  of  the  heart,  whether 
permanent  or  transient,  are  usually  benefited  by  alcohol." 
Alcohol  may  thus  be  of  value  in  forestalling  or  overcom- 
ing the  depressing  influences  of  the  toxins  produced  in 
certain  of  the  infectious  diseases,  and  in  shock.  In  the 
latter,  however,  especially  when  due  to  accident  or  to 
some  sudden  cause,  much  harm  rather  than  good  may  be 
done  by  the  administration  of  excessive  doses  of  alcohol,  on 
account  of  their  effect  upon  the  depressed  vital  centers,  and 
it  is  well  to  remember  tliat  better  and  speedier  results  will 
prol)ably  follow  small  doses  sutticiently  frequently  repeated. 
Alcohol  is  a  good  servant,  but  a  bad  master.  King 
Chambers  says  :  "  Let  alcohol  be  taken  never  as  a  stimu- 
lant or  preparative  for  work,  but  as  a  defence  against 
injury  done  by  work,  Avhcther  of  mind  or  body.  For 
example,  it  is  best  taken  with  the  evening  meal  or  after 
toil.  Let  the  increase  in  the  desire  for  and  the  power  of 
digesting  food  be  the  guide  and  limit  to  the  consumption 
of  all  alcoholic  liquids.  Let  the  forms  be  such  as  contain 
the  least  proportion  of  fusel  <ii].  T..(t  all  ^\•itll  an  heredi- 
tarv  tcndencv  to  hysteria  or  other  functional  diseases  of 


BEVERAGES.  277 

the  nervous  system  refrain  from  its  use  altogether,  even 
though  as  yet  in  good  health." 

Beverages. — To  comment  individually  upon  the  mul- 
titude of  non-alcoholic  and  non-stimulating  beverages 
that  are  now  more  or  less  generally  used,  is  both  imprac- 
ticable and  unnecessary,  nor  will  any  attempt  to  classify 
them  be  of  much  value.  For  the  most  part  they  serve 
only  to  please  the  palate ;  though  if  in  this  way  they 
bring  about  a  greater  ingestion  of  fluids  when  these  are 
needed,  their  service  cannot  be  considered  a  vain  one. 
For  it  has  already  been  stated  that  an  ample  supply 
of  drinking-water  or  other  fluids  taken  daily  and  habit- 
ually is  essential  to  the  satisfactory  removal  of  the 
various  waste  matters  from  the  body,  and  that  Mdthout 
it  the  latter  may  readily  develop  conditions  favoring 
disease. 

Moreover,  it  is  true  that  certain  gases  and  salts  held  in 
solution  in  some  beverages,  such  as  mineral  waters,  in- 
crease this  excretory  action,  and  may  be  highly  beneficial 
in  appropriate  cases ;  but  it  should  be  a  matter  of  caution 
that  where  such  therapeutic  results  are  thought  to  be 
necessary,  competent  medical  advice  should  be  the  guide 
as  to  the  kind  and  quantity  of  the  agents  used.  This 
comment  is  justified  by  the  fact  that  of  late  many  sub- 
stances possessing  decided  physiological  power  have  been 
advertised  and  sold  in  the  form  of  one  beverage  or 
another  directly  to  the  laity,  who,  being  incompetent  to 
judge  as  to  whether  or  not  such  substances  are  actually 
needed  in  their  individual  cases,  may  do  themselves 
much  harm  in  this  way. 

Only  such  beverages,  then,  as  are  quite  simple  in  their 
nature  or  as  are  advised  by  competent  medical  authority 
should  be  used.     If  they  are  artificially  made  and  water 


278  STIMULANTS  AND  BEVERAGES. 

is  the  solvent  fluid,  as  it  will  be  in  most  cases,  there 
should  also  be  certainty  that  it  comes  from  a  clean  and 
safe  source,  lest  it  carry  the  germs  of  disease.  There  is 
no  doubt  that  frequently  the  cheaper  bottled  drinks  which 
are  dispensed  so  generally  are  made  from  water  that  has 
been  liable  to  more  or  less  dangerous  pollution,  and  there 
is  the  additional  risk  that  arises  from  the  imperfect  cleans- 
ing of  the  bottles  for  these  liquids  which  have  been  re- 
turned to  be  refilled.  A  little  thought  as  to  the  dangers 
which  do  exist  in  relation  to  this  matter  will  be  convinc- 
ing as  to  their  gravity. 

Many  of  the  most  popular  beverages  are  charged  with 
carbon  dioxide  under  compression,  and  the  fact  that  so 
much  of  this  gas  can  be  taken  into  the  system  in  this  way 
without  apparent  harm,  and  its  free  elimination,  would 
seem  to  be  additional  evidence  that  it  cannot  in  itself  be 
so  very  harmful  in  the  atmosphere,  even  when  in  propor- 
tions considerably  greater  than  the  normal. 

In  conclusion,  it  may  be  said  that  a  free  use  of  all  such 
beverages  as  are  known  to  be  clean,  safe,  and  wholesome 
will  probably  be  found  to  be  entirely  favorable  to  health 
unless  there  be  some  contraindicating  reasons  peculiar  to 
the  individual  himself;  and  that  their  substitution,  when- 
ever possible,  in  place  of  the  alkaloidal  and  alcoholic 
stimulants  is  to  be  commended  on  hygienic  as  well  as 
other  grounds. 


CHAPTEE    VIII. 

PERSONAL  HYGIENE. 

The  proper  consideration  of  this  subject  demands  an 
ample  volume  rather  than  the  limits  of  a  single  chapter, 
for  the  ultimate  aim  of  all  sanitary  work  is  the  preserva- 
tion and  betterment  of  the  health  of  the  individual,  and 
beside,  the  factors  that  aflPect  the  well-being  of  the  person 
are  so  multitudinous  in  their  number  and  in  their  phases 
that  no  brief  discussion  can  comprehend  them  all. 

However,  much  that  pertains  to  personal  hygiene  and 
that  requires  no  repetition  for  its  application  has  already 
been  given  in  the  preceding  pages ;  so  that  it  is  hoped 
that  if  the  reader  will  exercise  that  virtue  of  common- 
sense  and  reflection  that  is  so  essential  in  this  study,  the 
remarks  to  be  added  will  be  helpful  in  suggestion  and  in 
answering  many  questions,  even  though  they  may  not  be 
considered  in  any  way  as  complete  discussions  of  the 
respective  themes. 

Each  age  has  its  own  requirements,  and  that  which 
may  be  entirely  satisfactory  or  permissible  at  one  time 
may  not  be  so  at  another.  To  attain  the  best  results  it 
will  often  be  necessary  even  to  anticipate  with  prophv- 
lactic  measures  the  birth  of  the  child  ;  and  broadly 
speaking,  much  of  the  welfare  of  future  generations  lies 
in  the  care  of  those  now  living. 

One  of  the  gravest  sociologic  problems  of  the  day  is  as 
to  how  far  the  State  is  justified  in  restricting  or  preventing 

279 


280  PERSONAL  HYGIENE. 

the  propagation  of  the  defective  or  degenerate  of  the 
human  race ;  and  though  the  time  may  not  be  ripe  for 
the  law  to  take  positive  action  in  these  matters,  it  is  the 
duty  of  every  sanitarian  to  use  his  utmost  efforts  to  the 
end  that  only  the  healthy  and  the  normal  may  continue. 

The  advances  in  physiologic  and  biologic  science  in  re- 
cent years  have  done  much  for  all  humanity,  but  in  no 
respect,  perhaps,  have  they  been  of  more  service  than  in 
determining  the  great  influences  of  heredity  and  en- 
vironment and  in  establishing  the  fact  that  the  presence 
or  absence  of  disease  is  oftentimes,  if  not  always,  due  as 
much  to  the  predisposing  conditions  and  physical  status  of 
the  individual  as  to  external  and  exciting  causes.  What 
may  cause  only  a  trifling  ill  in  one  may  bring  about  most 
serious  evils  in  another  whose  estate  is  not  so  fortunate. 

Life  has  been  defined  as  the  power  of  an  organism  to 
adjust  continually  its  internal  conditions  to  its  external 
conditions,  and  as  long  as  this  is  done  satisfactorily  life 
persists.  The  secret  of  personal  hygiene  and  health,  then, 
must  lie  in  determining  the  relationship  between  the  in- 
ternal and  external  conditions  of  the  individual's  organism, 

"  Know  thyself"  is  advice  good  for  the  body  as  well 
as  for  the  mind  or  soul,  and  knowledge  of  the  right  kind 
can  do  no  harm.  He  who  knows  his  personal  and  physi- 
cal nature  and  acts  accordingly  is  well  equipped  to  figlit 
against  the  ills  of  life,  and  the  study  of  the  relationship 
above  referred  to  will  help  the  thinking  man  so  to  care 
for  himself  that  in  all  probability  his  days  will  be  pro- 
longed. 

But  a  caution  or  two  must  be  interpolated  here.  It  is 
well  known  that  "  expectant  attention  "  too  persistently 
directed  toward  a  certain  organ  may  lead  to  decided  altera- 
tions or  disturbances  in  the  functions  of  that  organ  ;  and 


IMPORTANCE  OF  SELF-STUDY.  281 

again,  unless  one  well  understands  the  mysteries  of  human 
physi<^logy,  a  little  imperfect  or  insufficient  information 
in  this  respect  may  lead  to  the  assumption  or  pursuit  of 
habits  and  practices  actually  dangerous  to  health.  Too 
much  ill-advised  care  and  attention  may  be  just  as  full 
of  risk  as  too  little,  and  physiological  egotism  without  a 
sound  basis  may  have  a  bitter  reward. 

What  is  needed  is  that  each  one  should  study  care- 
fully the  phenomena  of  his  daily  life,  should  determine 
accurately  the  purpose  and  reason  of  each  of  the  respec- 
tive functions,  and  then,  not  forgetting  their  interde- 
pendence upon  one  another  and  that  all  should  work  in 
harmony,  should  endeavor  to  do  that  which  will  best 
facilitate  the  functional  activity  with  the  least  expenditure 
of  energy. 

There  are  a  number  of  ways  in  which  the  study  of  per- 
sonal hygiene  may  be  advantageously  pursued,  but  for 
practical  purposes  one  of  the  best  is  to  consider  it  with 
respect  to  the  main  groups  of  organs  and  functions  of  the 
body,  keeping  always  in  mind,  however,  the  correlation 
of  these,  and  that  no  part  of  the  body  can  be  entirely 
independent  of  the  rest.^  Nevertheless,  the  hygiene  of 
infancy  is  a  study  by  itself,  for  it  is  in  that  epoch  of  life 
that  the  plastic  constitution  can  be  and  is  moulded  most 
readily  by  all  the  influences  of  the  environment,  whether 
for  good  or  evil,  and  it  is  at  that  time  that  salutary  efforts 
are  to  be  made  with  greatest  hope  of  success  and  eventual 
good. 

Moreover,  the  principles  of  personal  hygiene  may  be 

1  This  method  has  been  followed  in  Pyle's  Manual  of  Personal  Hy- 
giene, to  which  the  reader  is  referred  for  an  admirable  discussion  of  the 
subject,  which  must  be  treated  all  too  briefly  here.  The  writer  would 
also  recommend  Starr's  Hygiene  of  the  Nursery  to  all  who  desire  specific 
and  authoritative  information  concerning  the  young. 


282  PERSONAL  HYGIENE. 

more  readily  taught  to  and  inculcated  in  the  young,  but 
with  much  greater  difficulty  can  we  affect  the  mature  or 
aged ;  for  we  are  all  creatures  of  many  hai:)its,  and  in  the 
mature  adult  the  impress  of  these  may  resist  to  the  utmost 
any  and  all  endeavors  to  modify  or  remove  them. 

Too  much  stress  cannot  be  laid  upon  the  fact  that  it  is  the 
constitution,  the  nature  of  the  inherent  tissue,  that  controls 
or  modifies  the  inception,  development,  and  progress  of 
many  of  the  ills  of  life,  and  that  whether  this  in  its  normal 
and  highest  vigor  be  a  bequest  of  heredity  or  be  attained 
only  1)y  the  most  careful  attention  to  details  in  the  practice 
of  the  art  of  hygiene,  it  should  always  be  looked  u])on  as 
the  most  valuable  physical  possession  of  the  individual. 

To  state  again  what  has  already  been  written  :  "  The 
essence  of  sanitation  is  to  secure  perfect  health,  to  increase 
the  inherent  power  to  resist  noxious  and  harmful  influ- 
ences, and  to  make  all  the  surroundings  and  environments 
of  the  body  pure  and  free  from  depressing  factors." 

With  this  preface,  the  following  discussions  are  added 
in  the  hope  that  they  may  be  of  assistance  in  determining 
the  Avay  of  riglit  ]i\iiig  and  in  securing  the  welfare  and 
health  of  each  individual. 

Heredity. 

Jn  the  broadest  .sense  heredity  is  a  characteristic  jointly 
possessed  by  two  cells,  furnished  by  respective  parents, 
whidi  join  and  form  a  fused  cell,  wdiich  carries  on  its 
evolution  under  certain  governing  impressions  indelibly 
stamped  l)y  the  two  parental  lines  of  descent ;  but,  in  the 
ordinary  use  of  the  term,  it  may  be  defined  as  the  trans- 
mission to  the  offspring  from  jiarent  or  ancestor  of  a  trait, 
type,  temperament,  characteristic,  or  predisjiosition  which 


HEREDITY.  283 

has  a  governing  or  influencing  effect  upon  the  growth  or 
nature  of  that  offspring.  This  transmitted  impression 
may  be  either  for  good  or  for  evil. 

'•'  It  shows  an  incorrect  conception  of  the  law  of  hered- 
ity to  look  for  a  return  of  identical  phenomena  in  each 
new  fjeneration."  ^  Also,  "  we  do  not  mean  exclusivelv 
by  heredity  the  very  complaint  of  the  parent  transmitted 
to  the  children,  with  the  identical  symptoms,  both  physi- 
cal and  moral,  observed  in  the  progenitors.  By  the  term 
heredity  we  understand  the  transmission  of  organic  dis- 
positions from  parents  to  children."-  In  true  hereditary 
disease  the  faulty  conditions  must  be  transmitted  in  the 
gerin-pkisiii,  and  not  be  due  simply  to  accidental  factors 
aifecting  the  embryo  during  its  fcetal  development. 

Consequently,  as  hygienists,  we  must  use  the  influence 
and  power  that  we  have  to  further  the  transmission  of 
beneficial  or  elevating  characteristics  only,  and  to  prevent 
the  bequest  of  harmful  influences  and  hereditary  diseases 
to  the  generations  to  come.  "  The  germ  of  the  unborn 
infant  must  be  complete  and  untainted  in  all  its  nature, 
otherwise  we  cannot  hope  for  a  vigorous  and  perfect 
growth  or  development." 

As  the  familv  is  the  foundation  of  the  State,  and  society 
is  a  congregation  of  men  for  the  purpose  of  acquiring 
greater  power  and  more  comforts  through  mutual  co- 
operation, the  latter,  wliether  domestic  or  civil,  has  some 
right  to  make  men  understand  that  they  must  care  for  the 
health  of  the  generations  to  follow,  and  to  enact  reasonable 
laws  looking  to  the  prevention  or  obliteration  of  transmis- 
sible infirmities.  And  history  seems  to  show  that  no  great 
nation  has  ever  been  destroyed  or  overwhelmed  until  its 

1  Moreau,  Psychologic  morbide. 

2  Morel,  Traite  des  Degcnerescences. 


284  PERSONAL  HYGIENE. 

people  had  first  neglected  or  abused  the  laws  of  hygiene, 
heredity,  and  sociology. 

Marriage. — We  find  that  a  married  couple  have  gener- 
ally, beside  themselves,  the  welfare  of  five  human  beings 
within  their  keeping.  To  produce  healthy  children  and 
ones  not  prone  to  disease,  both  parents  should  possess  good 
constitutions,  and  they  should  take  great  care  not  to  weaken 
these  by  excesses  of  any  kind,  physical  or  mental,  nor,  as 
far  as  lies  in  their  power,  by  any  chronic  disease.  It  is 
evident  that  children  of  parents  that  have  been  conscien- 
tious observers  and  followers  of  ^STature's  laws  must  have 
a  better  chance  for  health  and  superiority  all  their  lives. 

In  this  climate  the  proper  age  for  marriage  is  consid- 
ered to  be  about  twenty-four  or  twenty-five  for  the  man, 
and  nineteen  or  twenty  for  the  woman,  though  this  must 
vary  with  the  state  of  development  of  the  parties  con- 
cerned. Some  of  both  sexes  mature  at  a  considerably 
earlier  period  than  do  others,  and  it  would  be  unjust  to 
say  that  they  were  not  fit  fir  the  duties  of  marriage  till 
they  reached  the  age  of  the  maturing  of  slower-growing 
ones.  Usually,  however,  before  the  ages  given,  develop- 
ment is  not  complete  and  the  whole  organism  is  in  a 
transition  state.  We  know  that  the  use  of  any  organ  be- 
fore it  has  attained  its  complete  growth  or  development  is 
very  apt  to  cause  exhaustion,  or  perhaps  premature  de- 
generation of  that  organ,  and  we  cannot  but  believe  that 
children  developed  in  iiniiiatiire  sexual  organs  must  be 
deficient  in  vital  force  and  energy.  It  is  often  noticeable 
that  a  chihl  apparently  strong  and  vigorous  may  have  but 
little  power  to  resist  disease  or  may  even  l)e  strongly  predis- 
posed to  some  infirmity  ;  in  such  cases  there  will  likely  be 
some  defect  or  taint  in  the  j^arent  stock. 

Distinguishing   characteristics  are  more  likely  to  be 


INHERITED  AND   CONGENITAL  DISEASES.       285 

transmitted  in  the  early  married  life  of  parents,  because 
their  organs  and  forces  are  then  more  vigorous ;  but  if  a 
couple  marry  when  quite  young  and  before  their  own  or- 
gans are  fully  developed,  their  elder  children  may  be  more 
deficient,  mentally  and  physically,  than  their  later  ones. 

Late  marriages  are  not  likely  to  be  so  fruitful  as  earlier 
ones,  possibly  owing  to  the  increased  difficulty  of  parturi- 
tion on  the  part  of  the  mother  and  her  consequent  unwill- 
ingness to  undergo  the  ordeal  more  than  a  few  times. 
But  healthy  middle-aged  persons,  who  have  married  late, 
may  have  even  healthier  children  than  those  who  have 
married  too  early. 

In  features,  constitution,  sense-organs,  shape  of  head, 
etc.,  the  child  is  most  apt  to  resemble  the  father ;  while 
it  will  likely  follow  the  mother  in  the  shape  of  the  trunk 
and  in  the  formation  of  internal  organs.  The  character 
and  mental  qualities  of  the  child  may  come  from  either 
parent  or  from  both.  Maternal  impressions  during  preg- 
nancy undoubtedly  often  have  a  marked  effect  upon  the 
coming  infant. 

So  also  do  maternal  toxaemias  or  other  depraved  con- 
ditions of  the  mother's  system,  though  occasionally  such 
influences  apparently  do  not  do  as  much  harm  as  we 
would  anticipate.  There  may,  however,  even  be  actual 
and  direct  infection  of  the  child  through  the  placenta. 
In  fact,  "  intrauterine  infections  and  modifications  of  the 
foetus  are  more  frequent  and  more  important  than  con- 
ditions of  true  inheritance  of  disease."  ' 

Inherited  and  Congenital  Diseases. — Hereditary  in- 

fiuences  are  generally  transmitted  directly  from  parent  to 

child,  but  we  occasionally   find   a   cessation  of  a  trait  or 

predisposition  for   one    or   more  generations  and  then  a 

1  McFarland . 


286  PERSONAL  HYGIENE. 

recurrence.  To  such  a  peculiarity  we  give  the  term 
atavism.  "A  family  history  of  less  than  four  generations 
has  only  a  limited  value." 

A  malady  may  be  truly  congenital — that  is,  existing  at 
i)irth  and  transmitted  directly  from  parent  to  offspring — 
as  syphilis,  structural  deformity,  mental  or  nervous  defect, 
etc.  ;  or  there  may  only  be  an  inherited  predisposition  to 
the  disease,  as  toward  tuberculosis,  etc.  Physicians  have 
thus  a  twofold  duty  :  first,  to  do  all  they  can  to  guard 
against  the  transmission  of  such  diseases ;  second,  to 
combat  the  disease  or  any  tendency  to  it  as  soon  as  the 
first  symptoms  thereof  are  discovered  or  it  is  suspected 
in  the  child.  The  first  duty  can  be  accomplished, 
theoretically,  by  preventing  generation  and  production 
on  the  part  of  those  unfit  to  produce  healthy  offspring, 
and  practically,  within  certain  limits,  by  fighting  the 
causes  and  their  effects  in  the  parent  individual,  especially 
at  the  ages  or  times  when  these  have  the  greatest  force  or 
are  most  apt  to  manifest  themselves.  For  the  second,  the 
child  must  be  immediately  placed  in  the  most  favorable 
hygienic  surroundings,  and  everything  possible  done  to 
prevent  the  further  development  of  the  disease  or  predis- 
position. In  many  cases  such  early  interference  will 
accomplish  much  good,  and  the  disease  may  be  averted 
entirely.  Esjiecially  is  this  true  of  those  inheriting  the 
tuberculous  diathesis. 

Too  often  the  chihl  of  a  tuberculous  parent  is  exposed 
after  birth  to  the  same  conditions  that  served  to  develop 
tlic  disease  in  the  parent,  and  its  inherited  predisposition 
to  the  malady  is  intensified  by  the  environment  of  a  damp 
and  undrained  soil,  a  dark  and  unventilated  house,  etc., 
and  by  insufficient  or  im]iroper  food  until  infection  is 
all  too  easily  acquired,  and  the  child  that  might  have 
been   saved    becomes  an   early   victim  of  the  ignorance, 


INHERITED  AND   CONGENITAL  DISEASES.      287 

carelessness,  or  neglect  of  those  who  should  have  fostered 
it  with  extremest  care  and  solicitude.  On  the  other  hand, 
tlie  apparently  complete  eradication  of  the  transmitted 
predisposition  from  many  children  whose  inheritance  has 
been  as  bad,  but  who  were  promptly  removed  from  the 
unsanitary  environment  of  their  birth,  shows  how  much 
this  one  influence  may  work  for  good. 

The  most  important  of  the  supposedly  hereditary  or 
transmissible  affections  are  syphilis,  tuberculosis,  scrofula, 
cancer,  gout,  hysteria,  epilepsy,  certain  physical  deform- 
ities, certain  skin  diseases,  insanity,  and  criminal  tenden- 
cies of  various  kinds.  But  do  not  forget  that  what  may 
appear  to  be  a  direct  and  actual  inheritance  of  a  disease 
may  only  be  the  production  of  the  disease  in  that  person 
by  the  same  agents,  environments,  and  morbid  conditions 
as  caused  or  favored  the  disease  in  the  parent.  However, 
even  here  there  is  very  possibly  a  transmitted  predisposi- 
tion to  the  acquirement  of  the  disease,  rendering  it  all  the 
more  easy  for  it  to  manifest  its  symptoms  upon  slight  prov- 
ocation. Therefore,  there  should  be  no  marriage  between 
persons  inheriting  predispositions  to  the  same  disease,  espec- 
ially if  they  be  relatives,  and  "a  person  affected  with  heredi- 
tary or  well-marked  constitutional  syphilis,  or  having  a 
strong  consumptive  taint,  or  tendency  to  mental  unsound- 
ness, should  not  marry  at  all." 

Defective  eyesight  is  very  apt  to  be  transmitted  to 
children,  and  the  latter  should  be  carefully  examined  and, 
if  necessary,  fitted  with  proper  glasses  before  being  placed 
at  school  or  at  any  work  requiring  much  use  of  the  eyes. 

Infirmities  which  do  not  prevent  marriage  from  being 
fully  accomplished,  or  which  do  not  tend  to  the  degenera- 
tion of  the  offspring,  are  not  good  reasons  alone  for  for- 
bidding marriage,  but  all  that  have  such  a  tendency  are. 


288  PERSONAL  HYGIENE. 

A  man  should  not  marry  a  woman  too  far  advanced  in 
life,  nor  one  that  is  very  feeble,  delicate,  or  deformed, 
especially  as  to  the  chest  or  pelvis.  Hysteria,  convul- 
sions, and  epilepsy  due  to  organic  disease  should  prevent 
a  woman  from  marrying,  though  some  extremely  nervous 
and  hysterical  Asomen  are  much  benefited  by  marriage 
and  have  healthy  children.  So  with  many  women  who 
have  uterine  congestions  and  displacements  before  mar- 
riage. 

Evidence  seems  to  indicate  that  marriage  between  rela- 
tives is  reprehensible,  and  that  the  danger  increases  with 
the  nearness  of  the  relationship,  since  the  children  of  such 
marriages  are  prone  to  disease  and  to  defects  in  the  sense- 
organs,  especially  the  eye  and  ear,  or  in  mental  qualities. 
But  upon  closer  investigation  it  is  probably  more  nearly 
true  that  "  the  objection  to  consanguineous  marriages  lies 
not  in  the  bare  fact  of  the  relationship  (of  the  parties  con- 
cerned), but  in  the  fear  of  their  having  similar  vitiations 
of  constitution."  Few  families  or  persons  are  absolutely 
healthy  or  free  from  taint,  and  "  it  may  safely  be  asserted 
that  when  both  parents  are  possessed  of  a  physiologic  or 
pathologic  congenital  characteristic,  that  characteristic  is 
almost  certain  to  be  repeated  in  an  aggravated  form  in  the 
offspring."  ^  We  can,  accordingly,  easily  understand  that 
"  in  consanguineous  marriages  the  real  danger  is  in  the 
strong  probability  that  both  parents  have  some  distinct 
taint  of  degeneration,  wliich  is  liable  to  be  increased  in 
their  children,  l)ut  which  might  possibly  disappear  if  each 
married  a  person  not  bearing  the  same  or  some  closely 
allied  character.  The  marriage  of  two  individuals  of  the 
phthisical  type,  whose  families  were  strangers  to  each 
other,  would  be  as  productive  of  evil  as  the  marriage  of 

1  Lawrence  Irwell,  Philadelphia  Medical  Journal,  July  21,  1900. 


EXERCISE.  289 

fir^t  cousins  who  were  phthisically  inclined."  ^  However, 
any  advice  on  the  subject  must  depend  upon  the  special 
circumstances  in  each  case,  but  chiefly  on  the  health  and 
degree  of  relationship  between  the  parties. 

Exercise. 

Exercise  is  generally  considered  to  mean  simply  the 
action  of  the  voluntary  muscles,  but  it  has  a  wdder  mean- 
ing than  this.  Every  organ  in  the  body  is  capable  of 
being  exercised  in  some  way  or  other ;  and  if  not  prop- 
erly exercised,  an  abnormal  state  is  almost  certain  to 
ensue.  ^'  Life  is  organization  in  action."  Each  organ  has 
its  own  special  stimulus,  and  if  this  be  normal  in  amount 
and  character,  we  should  have  health.  Also,  the  trained 
use  of  an  organ  makes  it  more  effective  in  the  performance 
of  its  functions.  But  deficiency  in  exercise  favors  a  lack 
of  nutrition,  wasting  in  size,  and  eventually  degeneration 
of  tissue  ;  while,  on  the  other  hand,  too  much  work  may 
favor  hypertrophy  and  tissue  degeneration. 

Proper  muscular  exercise  is  highly  beneficial  to  health, 
and  in  the  end  actually  necessary  to  the  proper  perform- 
ance of  functions  in  other  organs;  it  is  consistent  with 
and  necessary  to  "health.  But,  to  be  of  value,  the  exercise 
must  not  only  be  regular,  but  must  also  consist  of  move- 
ments of  sufficient  force  to  necessitate  energetic  contraction 
of  the  muscles  ;  we  must  do  work.  This  necessitates  resist- 
ance as  an  element,  and  we  may  define  physical  exercise 
as  voluntary  labor.  We  need  the  resistance  to  obtain  the 
proper  contraction  of  the  muscles,  the  contraction  for 
their  disintegration,  the  disintegration  for  their  renewal, 
etc. ;  for  we  know  that  upon  the  constant  destruction 
and   disintegration  of  tissues   depends   their   subsequent 

1  Lawrence  Irwell,  Philadelphia  Medical  Journal,  July  28,  1900. 
19 


290  PHYSICAL  HYGIENE, 

renovation,  and  that  the  strength  and  vigor  of  all  parts 
of  the  body  and  of  the  whole  depend  upon  its  newness. 

Beside  the  fact  that  proper  physical  exercise  makes  the 
voluntary  muscles  larger,  harder,  stronger,  and  more 
quickly  responsive  to  the  will,  and  that  it  increases  the 
functional  capacity  of  the  involuntary  muscles  employed, 
it  largely  promotes  health  and  strength  by  quickening  the 
^rculation  and  increasing  the  respiratory  powers.  Dur- 
ing muscular  action  (contraction)  there  is  a  conversion  of 
potential  energy  into  motion,  a  call  for  more  food,  an  in- 
creased demand  for  and  consumption  of  oxygen,  and  an 
increased  production  of  and  elimination  of  carbon  dioxide 
and  other  waste  matters. 

This  increased  demand  for  oxygen  and  elimination  of 
carbon  dioxide  necessitate  increased  action  of  the  respira- 
torv  organs — the  luuffs,  and  this  is  one  of  the  greatest 
advantages  of  physical  exercise.  The  respirations  are  in- 
creased in  frequency  and  depth,  the  lungs  expanded,  the 
air  vessels  flushed  out  and  refilled  with  each  inspiration. 
Doubtless  many  cases  of  pulmonary  tuberculosis  could  be 
prevented  or  cured  if  only  people  could  be  taught  to  take 
sufficient  and  suitable  exercise  and  to  breathe  properly,  for 
we  rarely  find  the  lungs  fully  expanded  except  in  the  out- 
door worker  or  athlete.  Consequently,  the  movements  of 
any  given  exercise  should  be  with  speed  and  force  sufficient 
to  ({uicken  and  deepen  the  respiration  ;  and,  conversely, 
if  any  severe  exercise  is  to  be  undertaken  or  a  course  of 
training  begun,  special  care  nnist  be  had  to  develop  the 
lung  capacity. 

A  man  walking  at  the  rate  of  f^ir  miles  per  hour  in- 
spires five  times  as  much  air  as  when  reclining  at  rest, 
which  latter  amount  is,  for  an  adult,  about  480  cubic 
inches  per  minute.     Or,  as  Pettenkofer  has  shown,  a  man 


BENEFITS  FROM  PHYSICAL  EXERCISE.        291 

on  a  day  of  rest  absorbs  25  ounces  of  oxygen  and  throws 
off  32  ounces  of  carbon  dioxide  and  29  ounces  of  water ; 
on  a  day  of  work  he  absorbs  33.6  ounces  of  oxygen  and 
throws  oif  45  ounces  of  carbon  dioxide  and  72  ounces  of 
water.  In  other  words,  the  elimination  of  carbon  on  a 
work-day  is  more  than  three-fourths  of  a  pound. 

Muscular  exercise  is  necessary,  therefore,  for  the  proper 
elimination  of  waste  carbon  from  the  body,  and,  as  the 
action  of  the  muscles  is  checked  and  lessened  if  the 
carbon  dioxide  produced  by  their  action  is  not  immediately 
carried  off"  by  the  blood  and  eliminated  by  the  lungs,  it 
follows  that  during  exercise  there  should  be  nothing  to 
impede  the  circulation  or  the  action  of  the  chest  and 
lungs,  and  that  all  tightness  of  clothing,  especially  about 
the  waist,  neck,  and  chest,  should  be  avoided.  Moreover, 
inasmuch  as  the  amount  of  carbon  dioxide  and  other 
waste  matters  eliminated  is  so  very  much  increased  during 
exercise,  a  much  larger  amount  of  pure  air  is  needed,  and 
all  rooms  and  buildings  wherein  exercise  is  to  be  taken 
should  be  well  ventilated. 

After  exercise  an  increased  amount  of  carbonaceous 
food  and  of  water  must  be  supplied  to  replenish  the  sys- 
tem for  what  has  been  eliminated.  The  increase  of  carbon 
food  is  probably  best  given  in  the  form  of  fat  rather  than 
of  the  carbohydrates,  though  there  is  some  difference  of 
opinion  on  this  point ;  and  of  all  fluids,  water  is  doubt- 
less the  best  in  ordinary  cases  for  training.  As  a  general 
rule,  alcohol  is  harmful,  because  it  benumbs  and  deadens 
the  nerves  and  will,  and  because,  as  every  voluntary  im- 
pulse must  originate  in  the  brain,  anything  that  interferes 
with  the  communication  between  it  and  the  muscles  must 
lessen  the  promptness  with  which  they  respond  and  the 
consequent  efficacy  of  their  work.     The  use  of  a  small 


292  PERSONAL  HYGIENE. 

quantity  of  malt  liquor,  however,  as  a  tonic  or  after  the 
exercise  is  finished  may  not  be  harmful,  but  the  decision 
as  to  its  need  or  use  should  be  left  to  the  physician  or 
trainer  rather  than  to  the  one  taking  the  exercise. 

By  exercise  the  action  of  the  heart  is  increased  in  force 
and  frequency,  the  pulse  is  made  full  and  strong,  if  the 
work  be  not  too  excessive  or  sudden,  and  the  flow  of 
blood  and  other  fluids  is  increased  throughout  the  whole 
body.  As  long  as  the  heart  is  not  overtaxed  the  pulse- 
beats  are  regular  and  even,  though  suddenly  increased 
exertion  may  make  the  rate  very  rapid.  Ordinarily  exer- 
cise increases  the  rate  from  ten  to  thirty  beats  per  minute. 
Excessive  exercise  leads  to  palpitation  and  hypertrophy 
of  the  heart  (one  reason  why  any  extensive  training 
should  be  under  a  competent  trainer) ;  but,  on  the  other 
hand,  deficient  exercise  leads  to  a  weakening  of  the  heart 
muscle  and  heart  action,  and  probably  to  dilatation  and 
fatty  degeneration.  If  at  the  beginning  of  a  new  exercise 
the  heart  action  becomes  irregular,  rest  should  be  taken, 
and  the  exercise  then  begun  in  a  more  moderate  and 
gradual  way.  The  heart  stimulus  is  largely  due  to  the 
increased  amount  of  blood  in  its  cavities,  but  it  should  be 
remembered  that  the  venous  circulation  is  chiefly  due  to 
the  muscles.  "  Every  muscle  is  a  little  heart,"  and  these, 
by  their  contraction,  constantly  tend  to  drive  the  blood 
onward  to  the  true  heart  and  lungs. 

l^xcrciso  greatly  increases  the  amount  of  perspiration 
from  the  skin,  this  perspiration  containing  water,  salt, 
and  considerable  waste  matter.  The  evaporation  of  the 
water  tends  to  keep  the  body  cool,  but  on  account  of  the 
great  heat-production  tiiere  is  not  much  danger  of  chilling 
the  body  during  exercise.  As  soon  as  work  is  stopped 
heat-production  is  checked,  the   body  cools  off  rapidly, 


EFFECT  OF  EXERCISE    UPON  THE  BE  A  IN.      293 

and  then  there  is  danger  of  chilling  unless  more  clothing 
be  added.  Flannel  is  best  for  this  purpose  because  it  is  a 
non-conductor  of  heat  and  hygroscopic  and  so  prevents  too 
rapid  cooling  of  the  body.  Keep  the  skin  clean  so  that 
the  sweat-glands  may  be  unobstructed  in  the  performance 
of  their  functions. 

Exercise  increases  the  appetite,  partly  because  of  the 
increased  demand  of  the  muscles  for  food,  and  partly  on 
account  of  the  increased  circulation  of  the  blood  through 
the  vessels  of  the  alimentary  tract  and  the  liver,  this 
causing  a  more  perfect  digestion  of  food. 

If  exercise  be  taken  too  soon  before  meals,  either  the 
stomach,  by  calling  the  blood  from  the  exhausted  muscles, 
will  prevent  their  proper  repair  and  rest;  or  the  muscles, 
calling  the  blood  from  the  stomach,  will  prevent  the 
proper  formation  of  the  gastric  juice  when  food  is  intro- 
duced. If  exercise  be  taken  too  soon  after  eating,  it  is 
apt  to  prevent  the  flow  of  blood  to  the  organs  of  digestion 
and  the  formation  of  the  digestive  juices ;  or,  by  forcing 
the  contents  of  the  stomach  into  the  intestines  before 
gastric  digestion  is  completed  and  l^efore  the  food  has 
reached  a  condition  in  which  the  intestines  can  make  use 
of  it,  to  cause  intestinal  irritation  and  indigestion. 

Proper  physical  exercise  favors  a  symmetrical  brain 
development,  for  it  not  only  sends  more  blood  containing 
food  and  oxygen  to  this  organ,  but  exercise  of  the  func- 
tions of  the  centres  governing  the  action  of  the  muscles 
must  also  favor  the  growth  and  development  of  those 
centres.  "  Hand  culture,  apart  from  its  value  per  se, 
is  a  means  toward  more  perfect  brain  culture,"  and  exer- 
cise by  itself  alone  is  truly  educational,  although  this 
feature  of  it  may  be  more  fidly  developed  and  empha- 
sized by  proper  systems  and  methods.     The  great  trouble 


294  PEBSOXAL  HYGIESE. 

is  that  it  is  extremely  liable  to  he  misapplied,  misunder- 
stood, or  neglected. 

The  aim  of  training  should  be  to  increase  the  capacity 
of  the  lungs  and  the  breathing  power,  to  strengthen  the 
heart  and  the  circulation,  to  invigorate  the  brain  and 
nerve-centres,  to  improve  digestion  and  nutrition,  to 
make  the  muscles  more  powerful,  more  responsive  to  the 
will  and  their  capacity  for  endurance  greater,  and  to' 
lessen  the  amount  of  adipose  tissue.  Systematic  exercise 
also  helps  one  to  resist  disease,  because  by  it  waste  mat- 
ters are  carried  off;  pores,  glands,  and  organs  are  kept  at 
work  and  healthy,  and  active  tissues  take  the  place  of 
weak  and  slusrsrish  ones. 

Fatigue  is  due  to  lack  of  contractile  material  in  the 
muscles  to  continue  work,  to  the  exhaustion  of  nerve-force 
and  motor  imj^ulses  from  the  brain,  and  to  accumulation 
of  waste  products,  possibly  leucomains,  in  the  muscle. 

Active  exercise  is  that  brought  about  by  one's  own 
movements ;  passive,  that  produced  by  something  out- 
side or  collateral  to  one's  own  power. 

It  is  hard  to  determine  how  much  exercise  any  given 
person  ought  to  take,  as  tlie  personal  equation  varies  so 
much.  The  average  healthy  man  should  probal)ly  do 
work  equivalent  to  150  foot-tons  daily.  The  work  of 
walking  on  a  level  at  the  rate  of  three  miles  per  hour  is 
said  to  be  equal  to  that  of  raising  one-twentieth  of  the 
body-weight  through  the  distance  walked.  According  to 
this,  a  man  of  150  pounds  in  walking  one  mile  does  work 
equal  to  17.67  foot-tons,  and  his  total  daily  physical  labor 
should  be  equivalent  to  walking  about  nine  miles  at  the 
al)ove  rate  to  get  the  proper  amount  of  daily  exercise. 
This  seems  like  an  excessive  amount,  but  if  the  actual 
physical    work    of    one's    customary    vocation   be   taken 


BATHING.  295 

from  this,  it  will  not  leave  so  very  much  for  the  daily 
health-task ;  and  while  the  natural  disinclination  of 
many  to  exercise  grows  stronger  by  indulgence,  and  while 
urgent  reminders  are  wanting  and  the  evils  arising  from 
the  neglect,  abuse,  or  misuse  of  exercise  are  not  so  very 
immediate  or  apparent,  the  latter  are  still  certain  to  result, 
and  are  not  at  all  consistent  with  good  and  perfect  health. 

Bathing-. 

In  health  we  make  use  of  baths  and  bathing  for  the 
cleansing  of  the  body,  the  stimulating  of  the  functions  of 
the  skin,  and  as  a  tonic  to  the  whole  system.  A  suitable 
bath  properly  taken  is  exhilarating  and  thoroughly  enjoy- 
able. Baths  are  also  to  be  employed  in  sickness  as  a 
means  of  cure,  but  such  use  of  them  is  foreign  to  the 
present  discussion. 

H.  C.  AVood  says  :  "  Cleanliness  and  the  maintenance 
of  the  pi'oper  condition  of  the  skin  require  the  use  of  the 
bath  at  least  twice  a  week.  In  some  very  delicate  persons 
the  general  bath  produces  marked  depression,  but  this  can 
almost  always  be  avoided  by  the  use  of  very  hot  water. 
If  the  hot  or  warm  bath  be  employed  habitually,  it  should 
be  preferably  taken  at  night,  and,  unless  under  very  ex- 
ceptional circumstances,  the  hot  bath  should  always  be 
followed  by  cold  sponging  or  the  cold  shower-bath,  or  by 
a  plunge  into  cold  water."  The  temperature  of  a  cold 
bath  may  be  from  40°  to  75°  F. ;  a  tepid  bath,  75°  to 
85°  F.  ;  a  warm  one,  85°  to  100°  F. ;  a  hot  one,  from 
100°  to  110°  F.  A  cold  bath  is  taken  not  so  much  for 
its  cleansing  as  for  its  tonic  and  stimulating  eifects ;  the 
others  are  used  mainly  for  their  cleansing  properties, 
though  if  followed  by  the  cold  sponge,  shower,  or  dip,  the 
sense  of  exhilaration  produced  will  be  marked. 


296  PERSONAL   HYGIENE. 

Cold  l)aths  taken  immediately  after  physical  exercise 
while  the  body  is  still  warm,  but  after  perspiration  has 
ceased,  and  followed  by  a  good  rubbing  and  friction  of 
the  skin,  dispel  fatigue  and  give  a  sense  of  buoyancy  and 
lightness.  The  shock  of  the  first  contact  of  the  water 
with  the  skin  is  but  momentary,  and  can  be  withstood 
by  most  persons  unless  there  be  serious  organic  disease ; 
and  the  reaction  produced  certainly  compensates  for  the 
primary  discomfort.  If  the  bath  be  taken  in  the  open 
air,  there  is  the  additional  benefit  of  a  plentiful  supply 
of  fresh  air  for  the  lungs,  of  tlie  physical  exercise  and  the 
increased  circulation  induced  by  swimming  or  combating 
the  surf,  and,  if  in  the  sea,  of  the  stimulation  of  the  skin 
by  the  salt  water.  In  fact,  sea-bathing  may  be  advan- 
tageous to  a  marked  degree  where  the  circulation  and 
action  of  the  skin  are  sluggish. 

Those  who  are  suljject  to  organic  heart  disease  should 
not  indulge  in  sea-l)atliing  nor  in  deep  fresh-water  bath- 
ing where  a  sudden  tax  may  be  made  u])on  the  strength 
and  the  heart  action  be  disturl)ed  or  checked.  Women 
who  are  menstruating  or  who  are  in  the  later  months  of 
])rcgnancy  sliould  not  take  cold  baths. 

I>atl)s  should  not  be  taken  too  soon  after  meals,  because 
digestion  may  be  lessened  or  entirely  stopped  by  the  blood 
being  called  from  the  stomach  to  the  skin  and  muscles, 
and  nausea  and  vomiting  thus  induced.  "  There  can  l)c 
no  doubt  that  many  of  the  cases  that  are  called  '  cram])s,' 
and  which  frequently  result  in  drowning,  are  due  to  tliis 
cause."*  In  cold  ])aths  the  head  should  be  immersed 
first,  "to  avoid  increasing  the  blood-pressure  in  the  brain 
t«o  greatly,  which  miglit  result  if  the  body  weVe  gradually 
immersed  from  tlic  feet  upward."^ 

'  Rolic's  Text-book  on  Hygiene.  ^  Ibid. 


BATHING.  297 

The  following  rules,  issued  by  the  Englisli  Royal 
Humane  Society,  are  worth  noting :  "  Avoid  bathing 
within  two  hours  after  a  meal,  or  when  exhausted  by 
fatigue,  or  when  the  body  is  cooling  after  perspiration. 
Avoid  bathing  altogether  in  the  open  air,  if,  after  having 
been  a  short  time  in  the  water,  there  is  a  sense  of  chilli- 
ness, with  numbness  of  the  hands  and  feet ;  but  bathe 
when  the  body  is  warm,  provided  no  time  is  lost  in  get- 
ting into  the  water.  Avoid  chilling  the  body  by  sitting 
or  standing  undressed  on  the  banks  or  in  boats  after  hav- 
ing been  in  the  water.  .  Avoid  remaining  too  long  in  the 
water,  but  leave  the  water  immediately  if  there  is  the 
slightest  feeling  of  chilliness.  The  vigorous  and  strong 
may  bathe  early  in  the  morning  on  an  empty  stomach ; 
the  young  and  those  who  are  weak  had  better  bathe  two 
or  three  hours  after  breakfast.  Those  who  are  subject  to 
giddiness  or  fainting,  or  who  sufier  from  palpitation  or 
other  sense  of  discomfort  of  the  heart,  should  not  bathe 
(out-of-doors)  without  first  consulting  their  physician."^ 

After  any  kind  of  a  bath  the  body  should  be  thor- 
oughly dried,  not  only  to  restore  and  accelerate  the  cir- 
culation of  the  skin  by  the  friction  and  to  prevent 
cooling  by  the  evaporation  of  the  water,  but  also  to  pre- 
vent chafing  and  eczematous  eruptions  where  the  skin  is 
subject  to  the  friction  of  clothing.  Warm  or  hot  baths 
sliould  not  be  taken  if  the  person  is  to  be  exposed  to  the 
cold  within  several  hours,  and  the  same  rule  applies  to 
Turkish,  Russian,  or  vapor  baths ;  so  the  former  had  best 
be  taken  in  the  evening,  and  the  latter  should  not  be 
taken  away  from  home,  especially  in  cold  weather,  unless 
the  bather  rests  for  a  time  after  the  bath,  and  then  wraps 
up  well  before  going  into  the  open  air. 

1  See  also  Sea  Air  and  Sea  BathiiiR,  by  John  H.  Packard. 


298  PERSONAL  HYGIENE. 

In  all  warm  baths  in  health  the  principal  object  is  to 
secure  the  cleansing  effects,  and  to  be  effective  their  use 
must  be  systematic.  The  pores  of  the  skin  are  self- 
cleansing  only  to  a  certain  degree,  and  the  free  use  of 
warm  water  is  most  beneficial  in  removing  dry  epithelium, 
sweat,  dirt,  and  grease.  If  the  pores  of  the  skin  are  ob- 
structed, there  are  not  only  irritation  and  eruptions  of  the 
skin  produced,  but  more  work  is  thrown  upon  the  kid- 
neys, and  these,  if  unsound,  will  break  down  the  quicker. 
Soft  water  is  to  be  preferred  for  ordinary  bathing  and 
washing,  because  it  often  prevents  or  lessens  cutaneous 
irritation,  and  because  it  saves  soap. 

A  Turkish  bath  consists  :  1.  Of  a  dry,  hot-air  bath 
at  a  temperature  of  from  120°  to  170°  F.,  or  even  higher, 
for  from  ten  to  thirty  minutes,  which  causes  in  most  per- 
sons profuse  perspiration  with  no  sense  of  discomfort, 
but  rather  a  pleasant  sensation.  After  this  come :  2.  A 
hot  shower-bath  to  wash  off  the  sweat.  3.  Shampooing, 
massage,  and  scrubbing  to  remove  thoroughly  all  dirt, 
loose  epithelium,  and  perspiration  from  the  skin.  These 
take  place  in  moist  air  at  from  100°  to  110°  F.  4.  A 
warm  shower-batli  gradually  changing  to  a  cold  one,  and 
then  a  thorough  drying  of  tlie  body  and  a  rest  for  a  quarter 
or  half  an  hour.  A  Russian  bath  differs  from  this  only  in 
that  moist  air  at  150°  F.  or  under  is  used  instead  of  dry 
air  for  the  first  batli. 

It  has  been  said  "  tliat  a  person  ought  never  to  stay  in 
either  the  hot-air  or  steam-room  if  in  any  wise  oppressed, 
or  to  use  very  cold  water  afterward  if  one  feels  any 
shrinking  from  it."  Nor  should  one  who  is  very  corpu- 
lent or  wlio  has  organic  heart  disease  take  a  Turkish  or 
Russian  batli  witliout  the  advice  of  a  physician.  But  for 
healthy  persons  they  are  quite  pleasant  and  in  most  cases 


CLOTHING.  299 

beneficial,  provided  they  are  not  taken  too  often  and  that 
one  does  not  indulge  in  them  too  long  at  a  time. 

The  terms  sun-baths,  mud-baths,  sand-baths,  and  pine- 
needle  baths  are  self-explanatory.  These  are  used  in 
treating  certain  diseases,  and  are  suj)posed  to  be  espe- 
cially beneficial  in  rheumatic  affections. 

Clothing. 

There  is  scarcely  anything  that  can  be  said  on  this 
subject  with  which  almost  every  one  of  ordinary  intelli- 
gence is  not  in  some  respects  conversant.  According  to 
Poore,  the  main  objects  to  be  sought  in  clothing  the  body 
are  :  "  1.  To  maintain  the  temperature  and,  by  preventing 
the  loss  of  animal  heat,  to  diminish  to  some  extent  the 
demands  for  food.  2.  To  allow  the  chief  heat-regulating 
mechanism — i.  e.,  the  evaporation  from  the  skin — to  pro- 
ceed with  as  little  hindrance  as  possible.  3.  To  allow  all 
muscular  acts  the  greatest  possible  freedom,  and  to  avoid 
the  compression  of  the  body  in  so  far  as  may  be  possible. 

4.  To  protect  the  body  from  heat,  cold,  wind,  and  rain. 

5.  To  disguise  as  little  as  may  be  the  natural  beauties  of 
the  human  figure."' 

The  substances  from  which  articles  of  clothing  are  usu- 
ally manufactured  are  wool,  silk,  cotton,  linen,  leather, 
and  furs,  although  almost  everything  that  can  possibly 
be  fashioned  to  suit  the  needs  or  fancies  of  the  wearer  is 
or  has  been  utilized  for  the  purpose.  Goods  of  all  manner 
and  kind  are  woven  from  the  first  four  substances  men- 
tioned, either  singly  or  in  combination  one  with  another, 
and  felts  are  made  from  wool,  hair,  or  fur,  these  latter 
being  made,  not  by  weaving,  but  by  an  interlacing  and 
matting  together  of  the  fibres  by  pressure  and  rubbing. 

1  Stevenson  and  Murphy,  Treatise  on  Hygiene. 


300  PERSOSAL   HYGIEXE. 

Wool. — In  a  general  sense  wool  is  probably  the  most- 
valuable  of  clothing  materials,  since  in  a  variable  climate 
or  -svhere  there  are  sudden  changes  of  temperature  it  is 
the  safest  for  the  wearer  to  use.  While,  taking  hbre  for 
fibre,  it  probably  does  not  vary  so  much  from  linen  or 
cotton  as  a  heat-conductor  as  is  generally  believed,  it  is 
usually  woven  in  such  a  way  as  to  entangle  large  quan- 
tities of  air  in  its  meshes,  thus  preventing  either  sudden 
lowering  or  raising  of  the  body-temperature,  since  dry  air 
is  an  especially  good  non-conductor  of  heat.  Moreover, 
wool  is  very  hygroscopic,  readily  taking  up  water  and 
perspiration  and  giving  them  oif  slowly,  thus  reducing 
the  cooling  by  evaporation  to  a  minimum  and  regulating 
the  heat-dissipation  of  the  body.  All  who  are  subject 
to  rheumatism  or  to  such  disturbances  of  health  as  are 
due  to  sudden  temperature-changes  should  wear  woollen 
garments  next  the  skin  tlie  year  round,  varying  the  thick- 
ness and  weight,  of  course,  to  suit  the  season  ;  and  children 
and  others  subject  to  digestive  disturbances  will  usually 
be  greatly  Ijenefited  by  the  constant  use  of  a  woollen  (or, 
in  case  that  is  too  heavy,  a  silken)  l)an(l  al)out  the  ab- 
domen. 

As  it  is  ordinarily  woven,  some  persons  cannot  tolerate 
wool  next  the  skin  on  account  of  its  irritating  properties. 
Those  latter  arc  obviated,  however,  if  the  undergarments 
1)0  made  of  pure  wool  woven  by  methods  similar  to  that 
introduced  bv  Jaeger,  or  of  a  mixture  of  avooI  or  cotton, 
or  1)V  wearing  a  net  garment  of  linen  or  cotton  next  the 
skin  and  underneath  the  Avoollen  under-clothing.  The 
Jaeger  method,  by  the  way,  is  said  to  provide  for  the 
escape  of  moisture  fntm  the  material  and  for  the  free 
permeation  of  air  tlu'ongh  its  interstices. 

Silk  is  an  excellent  non-conductor  of  heat,  and  is  almost 


MATERIALS    USED  FOR    CLOTHING.  301 

as  hygroscopic  as  wool,  so  that  it  is  suitable  material  from 
which  to  make  warm  clothing.  Its  great  natural  beauty 
and  the  facility  with  which  it  takes  coloring-matter  also 
make  it  desirable  from  an  sesthetic  standpoint,  while  its 
great  disadvantage  is  its  high  cost.  For  those  who  can- 
not wear  wool  next  the  skin  and  to  whom  cost  is  no  ob- 
jection, silk  is  an  excellent  material  for  undergarments. 

Cotton  is  probably  the  most  generally  used  for  clothing 
of  all  the  fibres.  It  is  not  so  hygroscopic  by  far  as  wool, 
but  it  is  hard  and  durable,  and  is,  above  all,  cheap,  so  that 
it  furnishes  the  bulk  of  the  clothing  for  the  masses.  If 
smoothly  woven  and  of  a  light  color,  it  makes  extremely 
cool  garments  for  warm  climates  or  seasons.  On  the 
other  hand,  if  warm  clothes  are  desired,  the  cotton  must 
be  woven  so  as  to  have  large  air-spaces  in  the  fabric,  thus 
making  it  resemble  the  ordinary  woollen  clothing  in  text- 
ure and  partly  in  function,  and  should  be  of  a  dark  color. 
Cotton  should  not  be  worn  next  the  skin  by  those  subject 
to  sudden  temperature-changes,  nor  during  exercise,  unless 
in  the  latter  case  it  is  changed  immediately  after  the  ex- 
ercise or  additional  clothing  is  added  to  the  body  to  pre- 
vent too  rapid  evaporation  and  cooling. 

Linen  is  valued  for  its  purity  of  color  when  bleached, 
and  for  its  durability.  It  is  more  expensive  than  cotton, 
and  its  hygroscopic  and  heat-conducting  properties  are 
about  the  same  as  the  latter.  It  is  especially  desirable 
for  use  in  clothing  for  hot  climates  and  for  articles  of 
dress  that  are  easily  soiled  and  need  frequent  cleansing. 

Furs  provide  extreme  protection  against  the  wind  and 
cold,  both  on  account  of  the  impermeability  of  the  skin 
and  of  the  large  quantity  of  air  entangled  in  the  fur  itself. 

Leather  is  utilized  for  foot-coverings,  etc.,  on  account 
of  its  durability,  pliability,  and  practical  imperviousness 


302  PERSONAL   HYGIENE. 

to  moistiirej  especially  when  oiled ;  and  in  cold  countries  is 
also  used  for  body  garments  on  account  of  its  resistance 
to  the  wind  and  the  efficacy  with  which  it  keeps  the  body 
surrounded  with  a  layer  of  warm  air. 

With  the  possible  exception  of  rubber,  which  is  espe- 
cially useful  for  the  protection  which  it  gives  from  wind 
and  rain,  other  materials  from  winch  clothing  is  made 
need  not  be  mentioned  here,  because  of  the  comparative 
rarity  of  their  use  and  their  close  resemblance  to  those 
already  named.  The  value  of  any  material  for  clothing 
purposes,  however,  may  be  said  to  depend  upon  the  slow- 
ness with  wdiich  it  permits  the  passage  of  heat  to  or  from 
the  body  and  the  evaporation  of  water,  the  amount  of  air 
its  meshes  contain,  its  impermeability  to  the  wind,  or  else 
its  special  adaptability  to  some  particular  purpose. 

Certain  materials  are  manufactured  from  combinations 
or  mixtures  of  two  or  more  of  the  four  fil^res  first  men- 
tioned, and  it  sometimes  becomes  necessary  to  distinguish 
these  one  from  another  and  to  determine  the  proportion 
of  each  in  the  goods.  This  is  done  by  microscopical  ex- 
amination, each  fibre  having  its  own  peculiar  character- 
istics, and  by  chemical  reactions.  Some  of  these  latter 
are  as  follows :  Wool  and  silk  dissolve  in  hot  liquor 
potassse  or  sodse  of  a  specific  gravity  of  1050,  while  cotton 
and  linen 'arc  not  affected.  Wool  and  silk  are  stained 
yellow  by  strong  nitric  or  picric  acid  ;  cotton  and  linen 
are  not.  Sulphuric  acid  affects  wool  but  little,  slowly 
dissolves  silk,  and  changes  cotton  or  linen  into  a  gelati- 
nous substance  that  is  colored  blue  by  iodine.  Hot 
concentrated  zinc  chloride  dissolves  silk,  but  not  wool ; 
and  copper  dissolved  in  ammonia  rapidly  dissolves 
silk  and  rf)tton,  linen  more  slowly,  but  only  slightly 
swells  wool. 


FASHIONS   OF  DRESS.  303 

Cloths  are  often  sophisticated  in  the  process  of 
manufacture,  and  their  value  greatly  lessened  thereby. 
\\'ool  is  mixed  with  "  shoddy/'  which  is  made  from 
old  and  used  woollen  rags  torn  asunder  and  then  respun 
%\ith  an  addition  of  fresh  wool ;  silk  is  heavily  weighted 
with  salts  of  tin,  iron,  or  with  other  substances ;  and 
cotton  and  linen  are  stifiened  and  glossed  with  an  exces- 
sive amount  of  starch,  white  earth  or  the  like.  Shoddy 
can  be  determined  by  the  use  of  the  microscope ;  the 
weighting  of  silk  by  chemical  reactions  and  solutions ;  and 
overstarching,  etc.,  of  cotton  and  hnen  by  washing  and 
drying. 

It  will  not  be  advisable  here  to  go  fully  into  con- 
sideration of  the  influence  which  the  shape  and  style  of 
the  individual  garments  of  ordinary  use  have  upon  health, 
for  that  would  require  a  much  longer  discussion  than  the 
present  space  permits ;  but  the  general  rule  may  be  laid 
down  that  each  article  of  clothing  should  be  adapted 
to  the  peculiar  needs  and  occupation  of  the  wearer,  and 
that  it  should  in  nowise  interfere  with  the  proper  develop- 
ment, use,  or  physiological  functions  of  any  part  of  the 
body. 

Trite  and  hackneyed  as  is  the  subject,  the  writer  feels 
that  he  would  be  wanting  in  the  performance  of  his  duty 
if  he  failed  to  condemn  the  habits  and  fashions  of  dress 
tliat  demand  undue  constriction  of  the  trunk  of  tlie 
body.  All  sanitarians  practically  agree  upon  the  impor- 
tance of  "  vital  capacity,"  as  measured  by  the  develop- 
ment and  extent  of  expansion  of  the  thorax,  in  determining 
the  constitution  and  health  of  the  individual.  But  not 
only  does  the  corset  harm  by  interfering  with  the  func- 
tions of  respiration  and  circulation,  but  it  also  deforms 
and  induces  even  more  serious  troubles  by  its  displacement 


304  PERSONAL   HYGIENE. 

of  the  abdominal  and  especially  of  the  pelvic  organs,  and 
by  the  grave  interference  with  the  nutrition,  tone,  and 
functions  of  all  of  these.  It  is  a  fair  challenge  to  any 
woman  who  declares  that  she  does  not  dress  too  tightly, 
to  ask  her  to  measure  honestly  her  waist  circumference 
and  expansion  both  with  and  without  the  garment  in 
question,  and  to  make  her  decision  accordingly.  And  it 
is  certainly  false  doctrine  to  teach,  as  is  so  often  done  to 
young  girls,  that  it  is  really  necessary  that  the  normal 
human  body  should  have  artificial  support.  The  natural 
muscles  kept  in  proper  training,  tone,  and  action  are  all- 
sufficient  to  give  the  most  perfect  and  most  beautiful 
human  form. 

When  exposed  to  the  sun's  rays  or  to  other  sources  of 
radiant  and  incandescent  heat,  fabrics  absorb  heat  irre- 
spective of  the  constituent  materials,  but  in  the  following 
order  as  regards  color  :  white,  light  yellow,  dark  yellow, 
light  green,  Turkey  red,  dark  green,  light  blue,  and  Ijlack, 
the  latter  color  absorbing  more  than  and  light  blue  almost 
twice  as  much  as  white,  the  material  in  each  case  being 
tlie  same.  In  the  shade  the  degree  of  absorption  depends 
more  on  the  material  than  on  the  color. 

Lastly,  it  should  be  rememl)ered  that,  as  disease  germs 
are  readily  conveyed  from  place  to  jdace  and  fi-oni  one 
person  to  another  by  the  clothing,  and  es])e('ially  by  that 
which  is  hygroscopic  by  nature,  care  should  be  taken  to 
keep  the  garments  in  as  cleanly  and  aseptic  condition  as 
possible,  to  disinfect  them  whenever  they  have  been  ex- 
posed to  infection,  and,  for  those  who  are  much  among 
the  sick  or  liable  to  infection,  the  use  of  smooth,  closely 
woven,  non-hygroscopic  over  or  outer  garments  that  can 
be  readily  cleansed,  such  as  those  made  of  cotton  or  linen, 
is  to  be  highly  reconnnended. 


LIGHT.  305 


Li£^ht. 


The  important  influence  of  sunlight  in  the  development 
the  maintenance  of  a  healthful  condition  in  all  higher 
organisms,  both  animal  and  vegetable,  is  well  known  by 
every  one,  but  as  yet  there  is  a  lack  of  information  as  to 
the  exact  physiological  methods  and  processes  which  are 
due  to  this  great  force.  We  know  that,  for  the  plants, 
chlorophyll  is  the  intermediary  agent  which  largely  assists 
in  the  conversion  of  carbon  dioxide  and  the  storage  of 
carbon  in  various  compounds,  and  that  the  presence  and 
action  of  this  chlorophyll  are  largely  dependent  upon  the 
light-supply ;  while  for  the  animal  kingdom,  and  espe- 
cially for  the  human  race,  it  is  evident  that  the  eifect 
of  sunlight  is  manifested  more  or  less  directly  in  the 
blood  and  skin,  though  the  whole  body  quickly  shows  a 
marked  appreciation  of  its  presence  or  absence.  But 
when  this  has  been  said,  there  is  little  else  that  can  be 
added  as  a  matter  of  positive  information.  No  one  knows 
just  how  the  pallid  and  anaemic  child  that  has  been 
reared  in  the  shade  and  dark  is  converted  into  the  tanned 
and  ruddy  picture  of  health  in  so  short  a  time,  but  the 
results  are  unquestionable. 

The  subject  demands  further  study,  and  it  may  not  be 
out  of  place  to  indicate  one  or  two  directions  in  which  the 
investigation  may,  perchance,  be  wisely  pursued. 

In  the  first  place,  there  has  doubtless  been  too  little 
appreciation  of  the  fact  that  sunlight  in  its  totality  has 
many  other  rays  of  force  than  those  which  manifest  them- 
selves alone  to  our  sense  of  sight.  The  existence  of  the 
ultra-violet  rays  and  the  fact  that  these  are  more  power- 
ful actinically  than  those  of  the  ordinary  spectrum  have 
been   satisfactorily  demonstrated,  and   the  only  question 

20 


306  PERSONAL  HYGIENE. 

is  as  to  what  the  true  physiologic  power  and  influence  of 
these  invisible  rays  may  be.  It  is  not  certain  at  present 
that  some  of  them  at  least  are  not  closely  related  to  the 
manifestation  of  force  discovered  by  Rontgen,  and  there 
is  good  reason  to  believe  that  the  penetrative  powers 
of  light  as  regards  the  human  body  are  not  fully  known 
or  appreciated.^  Nor  can  we  tell  how  much  of  that  power 
of  the  sun  whose  effects  we  feel  and  see  is  in  nature  on 
that  borderland  between  light  and  electricity  that  is  as 
yet  so  vague  and  unknown. 

Again,  the  destructive  effect  of  sunlight,  and  of  light 
from  minor  sources  as  well,  upon  the  germs  of  disease  and 
other  low  forms  of  life,  and  upon  their  toxic  products,  is 
now  a  matter  of  common  knowledge,  though  many  are 
not  aware  that  it  has  been  proved  that  this  germicidal 
action  of  light  is  directly  in  relation  to  its  actinic  power. 
Considering  this,  together  with  the  statements  in  the  pre- 
ceding paragraph,  may  we  not  surmise  that  hostile  organ- 
isms, even  in  the  deeper  tissues,  are  overcome  both  in  this 
way  and  by  the  improved  condition  of  the  blood  due  to 
the  light,  and  that  this  hypothesis  lielps  to  explain  the 
good  results  that  follow  the  open-air  treatment  of  many 
diseases  and  abnormal  conditions?  The  tubercle  bacilli 
are  especially  susceptible  to  its  influence,  and  every  one 
should  know  that  an  abundance  of  sunlight  is  just  as 
essential  to  the  tuberculous  patient  as  are  plenty  of  good 
food,  pure  air,  or  proper  clotliing. 

1  Some  cxiJorimcnts  by  the  author  and  by  numerous  others  seem 
clearly  to  indicate  that  some  of  the  radiant  energy  from  the  sun,  and  in 
l(!sscr  degree  from  othcsr  sources  of  light,  is  able  to  penetrate  substances 
hitherto  considered  opaque,  and  to  produce  phenomena  similar  to  those 
due  to  the  Ilontgen  ray.  Consequently,  if  the  experiments  referred  to 
are  well  founded,  the  penetrative  ability  of  this  energy,  as  regards  the 
human  tissues,  would  seem  to  be  more  than  probable.- 


I 


THERAPEUTIC   USE   OF  SUNLIGHT.  307 

Bie^  has  described  a  treatment  by  means  of  light,  and 
has  reported  some  interesting  results  and  apparent  cures, 
in  cases  of  lupus  of  the  skin  and  circumscribed  baldness 
(alopecia  areata).  He  states  that  the  power  of  the  chemic 
rays  to  kill  bacteria,  to  produce  an  erythema  or  inflamma- 
tion of  the  skin,  and  to  penetrate  the  skin  is  already 
proved.  But  the  strongest  light  of  summer,  unconcen- 
trated,  is  too  weak  to  produce  marked  results  quickly  in 
disease,  and  as  the  chemic  and  bactericidal  power  of  light 
is  mainly  in  the  blue,  violet,  and  ultra-violet  rays,  meas- 
ures are  taken  to  concentrate  and  intensify  these  by  means 
of  a  plano-convex  lens  filled  with  a  solution  of  copper- 
ammonium  sulphate.  This  also  cools  the  rays,  which 
would  otherwise  be  intolerable,  and  further  cooling  is 
secured  by  a  smaller  hollow  plano-convex  lens  of  quartz, 
through  which  water  is  made  to  flow  and  which  is  applied 
to  the  part  of  the  skin  under  treatment  and  on  which  the 
concentrated  rays  impinge.  That  the  treatment  promises 
much  for  the  future  seems  undoubted.  Finsen  has  also 
done  much  to  develop  the  treatment  of  disease  by  sunlight, 
and  his  methods  are  being  employed  in  this  country  as 
well  as  abroad. 

More  might  also  be  said  in  reference  to  the  possible 
and  probable  chemic  activity  of  the  light  in  and  upon  the 
metabolic  processes  of  the  animal  body ;  but  as  there  is 
still  the  uncertainty  of  hypothesis  and  theory,  it  may  be 
wiser  simply  to  leave  the  foregoing  suggestions  as  food 
for  thought  and  incentives  to  further  research  and  investi- 
gation. 

The  importance  of  an  abundance  of  daylight  in  all 
rooms  where  much   work   is   to   be  done  should  not   be 

1  British  Medical  Journal,  September  30,  1899.     Philadelphia  Medical 
Journal,  October  7,  1899. 


308 


PERSONAL  HYGIENE. 


overlooked.  Not  only  is  it  necessary  for  the  conservation 
of  the  influences  just  mentioned,  and  as  a  destroyer  of  path- 
ogenic organisms,  but  it  is  also  more  agreeable  and  safer 
for  the  eyesight  than  any  form  of  artificial  light  yet  de- 
vised. An  important  aid  to  the  illumination  of  dark  in- 
teriors has  been  the  recent  introduction  of  panes  or  plates 
of  glass  with  a  series  of  ridges  or  prisms,  which  refract 

Fig.  52. 


Action  of  prismatic  glass  in  projecting  light.    (Harrington.) 


and  diffuse  tiiroughout  a  room  light  which  would  otherwi.se 
illuminate  it  but  partially  or  not  at  all.  The  prisms  are 
made  with  various  angles,  and  may  be  placed  either  in 
the  ordinary  window  sash  or  in  projecting  canopies, 
according  to  whether  the  direct  light  from  the  sky  is 
obstructed  or  not.     (F'igs.  52  and  53.) 

The    relation    of  artificial    lighting   to  ventilation    has 


ARTIFICIAL    LIGHTING. 


309 


been  discussed.     In  addition  to  this  point,  the  quantity 
of  light  supplied  and  its  steadiness  have  an  important 


Fig.  53. 


1 1 

B 

1    1 

1  \ 

Diagram  of  American  three-way-prisms  for  refracting  and  diffusing  day- 
light: A,  inner  prismatic  surface;  D,  outer  refracting  lens  surface;  C,  profile 
or  section  of  A ;  D,  profile  or  section  of  B. 

bearing  on  the  hygienic  value  of  any  artificial  source  of 
illumination  that  it  may  be  necessary  to  employ. 


CHAPTER    IX. 

SCHOOL  HYGIENE. 

It  was  remarked  in  the  chapter  on  Personal  Hygiene 
that  the  best  time  for  applying  the  laws  of  hygiene  is  in 
the  days  of  childhood  and  youth,  for  then  the  whole  or- 
ganism is  plastic  and  yields  readily  to  both  external  and 
internal  impressions  and  forces. 

This  being  so,  the  great  influence  of  the  factors  common 
to  school  life  may  be  readily  conceived,  and  inasmuch  as 
the  average  child  will  be  subject  to  them  for  a  large  part 
of  from  eight  to  ten  or  more  years,  the  importance  of  a 
study  of  school  hygiene  will  not  be  denied.  It  concerns 
the  parent,  the  physician,  and  the  citizen,  and  its  inves- 
tigations must  consider  the  personal  hygiene  of  the  scholar, 
the  conditions  of  his  health,  his  habits,  the  amount  of 
work  done,  the  sanitary  environment  and  requirements 
of  the  school-room  and  building,  the  furniture,  the  venti- 
lation and  heating,  and  the  influence  of  all  these  upon 
the  individual's  state  and  development. 

Next  to  the  scholar  himself  and  his  parents,  these  mat- 
ters are  of  special  interest  to  the  physician,  for,  beside 
being  one  who  from  his  special  training  and  education  is 
often  called  to  act  upon  school  committees  and  boards  of 
education,  he  has  to  treat  many  disturbances  of  health  in 
the  young  which  have  their  origin  or  cause  in  the  harm- 
ful or  insanitary  conditions  of  scihool  life. 

There  are  disorders  to  which  all  (children  are  subject 
whether  in  school  or  out ;  but  a  special  class  are  markedly 
310 


INFLUENCE  OF  OVER-WORK  UPON  HEALTH.    311 

influenced  by  school  life  or  work,  and  to  these  abnormal 
conditions  we  may  give  the  term  "  School  Pathology." 
Of  some  of  these,  overwork  is  the  cause ;  others  are  set 
up  by  other  factors. 

Overwork,  coupled  with  depressed  vitality,  may  give 
rise  in  children  to  one  or  more  of  the  following  troubles  : 
dyspepsia,  headaches,  nervous  derangements,  chorea,  epi- 
lepsy, neurasthenia,  backaches,  menstrual  disorders,  and, 
in  some  cases,  consumption.  On  the  other  hand,  faulty 
arrangement  of  seats  and  desks,  improper  location  of 
windows,  blackboards,  etc.,  may  cause  spinal  and  other 
physical  deformities,  defective  eyesight,  etc.  Of  the  first 
class,  even  where  the  amount  of  work  may  not  seem  or 
may  not  really  be  too  much  for  the  capacity  of  the  child, 
worry  about  rank  or  over  an  approaching  examination 
may  have  a  harmful  effect  upon  a  nervous  temperament. 
This  is  especially  so  if  the  examinations  come  at  the  end 
of  a  spring  term,  when  the  scholars  are  all  more  or  less 
worn-out  and  debilitated.  The  forcing  process  should  be 
avoided  as  far  as  possible,  and  if  grades  are  to  be  given 
at  all,  they  should  be  as  much  as  possible  for  the  work 
and  attendance  during  the  term,  and  not  so  much  for  the 
actual  work  done  at  examination  time. 

Moreover,  young  children  should  not  be  kept  in  school 
for  too  many  hours  in  the  day,  nor  should  school  be 
looked  upon  by  parents  as  a  place  to  which  to  send  chil- 
dren to  keep  them  out  of  the  way  and  from  mischief. 
Edwin  Chadwick  has  shown  that  a  child  from  five  to 
seven  years  can  only  attend  to  one  object  for  about  fifteen 
minutes ;  one  from  seven  to  ten,  for  twenty  minutes ; 
from  ten  to  twelve,  for  twenty-five  minutes,  etc.,  and  that 
the  length  of  individual  lessons  and  likewise  the  total 
day's  work  should  be  arranged  accordingly.     The  very 


312  SCHOOL  HYGIENE. 

early  years  of  school  life  should  be  given  to  inculcating 
correct  habits  of  attention  and  of  morals  and  to  training 
the  will  and  powers  of  concentration  and  observation, 
rather  than  to  the  teaching  of  any  special  knowledge. 

But  it  is  probably  the  work  attempted  outside  after 
school  hours,  and  not  the  actual  work  done  in  the  school, 
that  is  most  responsible  for  the  breaking  down  of  health, 
especially  in  older  scholars.  In  Cleveland,  in  1881,  of 
186  girls  in  the  high  school,  29  per  cent,  of  those  who 
studied  less  than  two  hours,  70  per  cent,  of  those  study- 
ing from  two  to  four  hours,  93  per  cent,  of  those  study- 
ing from  four  to  six  hours,  and  100  per  cent,  of  those 
studying  over  six  hours  daily  out  of  school,  had  poorer 
health  while  at  school.  Of  these  same  girls,  the  per- 
centages of  those  whose  health  was  "  very  poor  while 
at  school,"  dividing  them  the  same  way  as  regards  over- 
work, were  respectively  14,  40,  66,  and  100  per  cent. 
This  loss  of  health  was  attributed  by  the  parents  to  stair- 
climbing,  irregularity  of  meals,  worry  about  rank  and 
examinations,  etc. ;  but  Goodell  says :  "  So  commonly  do 
I  find  ill  health  associated  Avith  brilliant  scholarship,  that 
one  of  the  first  questions  I  put  to  a  young  lady  seeking 
my  advice  is,  'Did  you  stand  high  at  school?'"  Another 
writer  says :  "  The  effects  of  anxiety  are  worse  than  carry- 
ing heavy  loads." 

In  fact,  one  of  the  leading  educators  of  the  country  has 
suggested  that  children  should  not  be  required  to  study 
reading,  writing,  or  drawing  before  the  age  of  ten  or 
eleven,  as  these  luring  into  action  and  use  the  close  appli- 
cation of  the  finer  sense  organs  and  faculties  which  are 
not  as  yet  fully  developed ;  but  he  advises  that  the 
instruction  of  the  earlicT  years  of  school  life  should  consist 
mainly  of  language  lessons,  history,  nature  studies,  and 


ILL  HEALTH  DUE  TO  SCHOOL-LIFE.  313 

such  others  as  may  be  taught  orally,  and  that  will  at  the 
same  time  develop  the  child's  powers  of  attention,  obser- 
vation, and  reasoning.  There  is  more  than  a  chance  that 
such  a  plan  of  instruction  would  not  only  secure  better 
results  from  the  teacher's  point  of  view,  but  that  it  would 
also  be  safer  for  the  scholar's  physical  organism. 

While  a  child  is  at  school  its  mind  should  not  be 
wearied  by  outside  tasks,  as  music  or  painting  lessons, 
nor  the  body  weakened  by  social  dissipations,  late  hours, 
and  indigestible  food.  Girls  are  more  susceptible  to  dis- 
turbances, and  are  more  subject  to  them,  because  they  are 
more  willing  to  undertake  extra  or  double  work  than  boys, 
and  because  they  are  more  ambitious  and  worry  more 
about  rank.  In  all  children  the  obtaining  of  good  health 
and  a  sound  constitution  is  of  the  first  importance.  Youth 
is  the  time  for  gaining  health,  not  for  losing  it ;  for  build- 
ing up  sound  bodies  and  constitutions,  not  for  breaking 
them  down,  and  school  life  should  always  have  the  former 
as  one  of  its  greatest  ends.  Of  what  use  is  all  the  learn- 
ing one  may  gain  before  the  age  of  eighteen,  if  there  be 
no  strength  to  use  it  afterward  in  the  battle  of  life  ? 

School  life  is  sometimes  responsible  for  dyspepsia  by 
interfering  with  the  regularity  of  meals,  the  children 
missing  the  midday  meal  and  having  to  depend  upon  a 
meagre  lunch,  often  of  sweets  and  indigestible  food.  This 
is  especially  important  when  the  rest  of  the  family  dine 
at  noon,  and  there  is  only  a  light  meal  served  in  the  even- 
ing. Again,  many  habitually  lose  their  breakfast  through 
fear  of  being  late,  or  else  bolt  the  food  without  masticat- 
ing it  and  gulp  down  hot  coifee  or  tea  before  starting  on 
a  run  for  school.  But  often  the  loss  of  appetite  is  due 
simply  to  lack  of  fresh  air  and  proper  exercise,  or  else 
to  the  nervous  condition  of  the  child,  which  is  sometimes 


314  SCHOOL  HYGIENE. 

such  as  to  interfere  with  almost  all  of  the  body  functions. 
Such  dyspepsias  are  to  be  treated  by  attention  to  the 
foregoing  points  rather  than  by  medicine. 

Headache  is  a  common  disturbance  among  school  chil- 
dren, and  may  be  due  to  any  one  of  several  causes,  among 
which  are  overwork — producing  irritability  and  disturb- 
ances of  cerebral  circulation — indigestion,  bad  air,  eye- 
strain, etc.  The  eyes  should  always  be  examined  when 
headaches  are  persistent,  and  any  defects  corrected  by 
proper  glasses.  Associated  with  the  headaches,  frequent 
bleeding  from  the  nose  may  occur  and  should  not  be  over- 
looked, as  it  may  indicate  circulatory  disturbance. 

One  of  the  most  common  symptoms  of  nervous  derange- 
ment is  sleeplessness  or  restless  sleep,  and  this  condition 
should  give  warning  that  something  is  wrong.  Folsom 
says  :  "  I  doubt  whether  there  is  an  exaggerated  preva- 
lence of  manifest  or  well-marked  diseases  of  the  nervous 
system  among  school  children.  If  due  to  the  school-drill, 
my  impression  is  that  they  come  for  the  most  part  later  in 
life,  after  the  children  have  left  school,  and  because  of 
constitutions  weakened  during  school  years,  instead  of 
strengthened  as  they  should  be."  Children  subject  to 
chorea  or  epilepsy  should  not  attend  school,  not  only  for 
their  own  sake,  but  also  for  that  of  the  other  children,  who 
may  be  unduly  affected  by  their  nervous  manifestations. 
Such  children  should  be  educated  quietly  and  cautiously, 
with  proper  treatment  and  plenty  of  out-door  life.  Neuras- 
thenia or  general  break-down  may  occur,  usually  from 
overwork,  and  especially  among  young  women.  It  may 
come  on  unexpectedly  after  the  examinations  at  the  end 
of  the  term,  when  the  strain  and  excitement  are  removed. 

Menstrual  disorders  are  also  apt  to  occur  among  girls 
that   are  being  overworked  mentally,  and  we  ought  to 


ILL  HEALTH  DUE  TO  SCHOOL-LIFE. 


315 


remember  that  the  system  is  undergoing  a  heavy  strain 
at  the  time  this  function  is  developing.  Also,  for  certain 
young  women  rest  from  customary  work  is  necessary  at 
the  time  of  the  periodical  recurrence,  and  excuses  for  ab- 
sence at  this  time  ought  to  be  freely  granted.    It  has  been 


Fig.  54. 


Position  assumed  in  writing  with  the  desk  too  high.    (Pyle.) 

well  said  that  "  girls  get  through  as  much  work  as  boys, 
working  in  their  own  way." 

The  development  of  consumption  may  be  due  to  the 
school  life,  though  it  is  hard  to  say  how  frequently  this 
is  the  case.  Bad  air  and  overwork  are  both  important 
factors  in  its  production,  and  if  these  are  forced  on  under- 
fed or  predisposed  children  the  disease  may  be  provoked. 
"  In  a  consumptive  family  the  steadfast  rule  should  be  that 
the  mind  be  wholly  subservient  to  the  body's  welfare." 


316  SCHOOL  HYGIENE. 

The  main  cause  of  spinal  and  other  deformities  and  de- 
fective eyesight  is  apt  to  be  found  in  faulty  construction 
of  seats  and  desks,  improper  location  of  windows,  etc., 
though  excessive  work  or  strain  may  maintain  a  low 
vitality  and  act  as  a  predisposing  condition.  The  latter 
point  is  shown  by  the  fact  that  spinal  curvatures  are  more 

Fig.  55. 


Position  assumed  in  writing  with  the  desk  too  low.    (Pyle.) 

prevalent  in  those  especially  prone  to  weakness  of  the 
muscles,  as  women  and  girls.  But  no  desk  or  seat  will 
remove  original  weakness  of  muscle  as  the  one  important 
predisposing  condition,  and  children  cannot  be  made 
strong  by  supports.  "  Spinal  curvature  is  not  only  a 
product  of  low  vitality,  but  does  harm  by  permanently 
fixing  vitality  at  a  low  standard." 

Improperly   arranged    seats  and  desks  not  only  often 
cause  spinal  deformities,  but  also  help  to  develop  defective 


INFLUENCE   OF  SCHOOL-FURNITURE.  317 

eyesight  by  causing  the  scholar  to  hold  the  book  too  near 
the  eyes  and  by  making  him  bend  his  head  so  that  the 
circulation  of  blood  is  impeded  and  ocular  congestion 
favored.  However,  no  seat  can  be  devised  in  which  a 
child  will  maintain  a  correct  or  "normal"  position  for 
any  but  a  short  time,  as  this  is  an  impossibility  for  young 
children;  but  the  aim  should  be  to  furnish  a  seat  in 
which  one  will  naturally  assume  the  correct  position  after 
having  temporarily  taken  any  other.  "  Movement  is  a 
child's  way  of  resting ;  rest  is  a  kind  of  work,  to  be  taught 
by  degrees."  Seats  should  have  backs  to  prevent  fatigue, 
but  a  comfortable  back  gives  support  to  the  lower  part 
of  the  spine  rather  than  to  the  shoulders  and  upper  part 
of  the  spine.  Many  foreign  authorities  advise  seats  with 
backs  only  high  enough  to  support  the  lower  part  of  the 
spine,  and  low  enough  for  the  scholar  to  rest  his  elbows 
upon  them  while  studying. 

The  following  points,  suggested  by  Lincoln,  are  worth 
noting :  "  1.  The  chair  is  often  too  high  for  young  schol- 
ars. The  most  convenient  plan  may  be  to  provide  foot- 
stools. 2.  The  seat  from  back  to  front  ought  to  be  long 
enough  to  support  the  whole  thigh.  A  more  or  less 
spoon-shaped  hollow  in  the  seat  is  commonly  thought  de- 
sirable. The  curve  of  many  settees  is  such  as  to  produce 
pain  at  the  point  where  the  tuberosities  of  the  ischium  rest 
on  the  wood ;  the  support  is  there  not  wide  enough. 
3.  Seats  must  have  backs.  The  straight,  upright  back 
reaching  to  the  shoulders  is  bad ;  a  straight  back,  slightly 
tilted,  is  not  bad.  American  seats  are  commonly  curved, 
with  curved  backs.  4.  The  edge  of  the  desk  should  come 
up  to  or  overlap  the  edge  of  the  seat.  The  recognition  of 
this  fact  is  a  recent  discovery.  5.  Most  of  our  best  desks 
are  too  high  relatively  to  the  seat,  doubtless  to  prevent 


318  SCHOOL  HYGIENE. 

the  pupil  from  stooping.  Something  is  gained  in  con- 
venience of  reading  by  this  plan,  but  it  interferes  with 
correct  p(Jsitions  in  writing.  The  elbows,  hanging  freely, 
should  be  only  just  below  the  level  of  the  lid."  For 
near-sighted  children  the  higher  desk  may  be  a  necessity 
in  writing ;  if  the  desk  is  made  low,  a  portable  writing- 
stand  may  be  placed  on  top  of  it  when  necessary. 

Windows  on  only  one  side  of  a  large  school-room  may 
not  give  sufficient  light  for  the  desks  most  remote  from 
them.  Consequently  there  should  be  windows  on  two 
sides,  preferably  adjoining  ones,  of  large  school-rooms. 
The  windows  should  be  at  the  back  and  to  the  left  of  the 
scholar,  thus  giving  the  best  light  upon  the  desk  for 
either  reading  or  writing.  They  should  not  be  placed  in 
front  of  the  scholars,  as  the  continuous  glare  is  very  trying 
and  injurious  to  the  eyes.  They  should  extend  almost  to 
the  ceiling  and  have  square  tops,  to  admit  as  much  light 
as  possible.  Blackboards  should  have  a  dead-black  sur- 
face, not  a  glossy  one,  and  should  be  on  the  sides  of  the 
room  on  which  there  are  no  windows.  Walls  should  be 
of  a  neutral  tint,  not  glaringly  white. 

Construction  of  School-houses. — The  principles 
already  given  as  to  ventilation,  heating,  water-supply, 
etc.,  apply  here  as  elsewhere.  From  1800  to  2500  cubic 
feet  of  fresl)  air  should  be  su]i}died  to  each  scholar  per 
hour.  In  cold  weather  this  should,  of  course,  be  satis- 
factorily warmed.  The  air-ducts,  both  iidets  and  outlets, 
must  be  sufficiently  large  to  change  the  air  without 
causing  injurious  and  uncomfortable  draughts ;  and  these 
ducts  should  l)e  as  short  and  free  from  bends  as  pos- 
sible, or,  better,  the  rooms  should  open  into  the  supply 
and  exhaust  shafts  directly.  The  air  may  be  warmed 
either  by  steam  or  hot-water  coils  or  by  a  furnace,  though 


CONSTRUCTION  OF  SCHOOL-HOUSES.  319 

preferably  by  the  former,  to  avoid  "  baking "  the  air, 
and  also  preferably  by  the  indirect  system.  There  is  no 
objection  to  having  additional  heating  apparatus  in  the 
scliool-room,  provided  it  is  guarded  so  that  the  scholars 
may  not  be  accidentally  burned.  Any  system  that  will 
give  a  sufficient  supply  of  fresh  air  properly  heated  will 
of  necessity  be  more  expensive  than  the  old  way  of  not 
ventilating  at  all  except  by  opening  the  windows  at  recess 
time,  but  experience  shows  that  the  increase  in  expense 
is  not  so  very  great,  as  so  much  heat  is  lost  by  opening 
the  windows  in  this  way,  and  the  benefit  to  the  children 
more  than  compensates  for  the  additional  outlay.  Country 
schools  may  be  heated  by  stoves  surrounded  by  sheet-iron 
drums,  and  ventilated  with  fresh  air  from  without  brought 
in  near  the  bottom  of  the  stove.  (See  Fig.  20.)  Passing 
up  between  the  stove  and  drum  the  air  is  warmed  and 
gives  good  ventilation  without  chilling  or  draught.  As 
great  a  length  as  possible  of  stovepipe  should  be  exposed 
in  order  to  get  the  full  benefit  of  the  heat  from  it. 

The  Smead  system  of  ventilation  and  heating  has  been 
used  with  satisfaction  in  many  schools  throughout  the 
country.  In  this,  the  air  after  being  warmed  and  brought 
into  the  school-rooms  at  a  level  a  few  feet  above  the  floor, 
circulates  through  them  and  is  finally  withdrawn  through 
registers  at  the  floor  level,  whence  it  is  carried  under- 
neath the  floors  to  large  outlet  shafts  in  which  a  draught 
is  constantly  maintained.  In  this  way  thorough  difl^u- 
sion  and  changing  of  the  air  in  the  school-rooms  are  se- 
cured, and,  moreover,  the  floors  are  kept  warm  by  the 
licat  from  the  air  wliich  is  passing  beneath  them  and 
which  would  otherwise  be  wasted.     (Fig.  56.) 

Ample  cloak-rooms  should  be  provided  for  every  school ; 
they   should  be  warm  and  well  ventilated  in  order  to 


320 


SCHOOL  HYGIENE. 


secure  the  rapid  drying  of  the  garments  in  wet  weather, 
but  they  should  not  commiuiicate  directly  with  the 
school-rooms  themselves,  if  it  can  be  avoided.  Provision 
should  also  be  made  for  readily  disinfecting  them,  and, 
in  fact,  the  whole  school  building  at  intervals  and  when- 
ever necessary. 

In    1897    at   Newcastle-upon-Tyne,   "the   experiment 
was   tried  of  closing  each  school,  where   scholars  were 


Fig.  56. 


Illustrating  the  Smcac!  system  of  ventilation. 

being  taken  ill,  for  a  few  hours  only,  long  enough  to 
allow  of  thorough  purification  and  the  sprinkling  of  the 
floors  of  class-rooms  with  disinfeetcmts.  This  disinfection, 
so  far  as  measles  was  concerned,  was  followed  by  the  ex- 
tinction of  the  disease  in  question."^ 

The  school-house  should  be  on  dry  and  well-drained  soil, 
as  dampness  is  not  only  (k'j)ressing  to  all  constitutions, 
'  American  Year-book  of  Medicine  for  1900,  pp.  543,  544. 


SCHOOL  SANITATION.  321 

but  is  also  an  important  factor  in  the  causation  of  phthisis 
and  strumous  diseases.  There  should  not  be  too  much 
shade  about,  and  as  many  rooms  as  possible  should 
have  sunny  exposures.  If  the  sunlight  is  annoying  dur- 
ing the  session,  it  may  be  excluded  by  inside  blinds  or 
shutters,  but  we  must  not  lose  sight  of  its  helpful  influ- 
ence in  the  destruction  of  bacteria  and  purification  of 
organic  matters. 

Where  sunlight  is  scanty  or  it  is  difficult  to  illuminate 
the  school-rooms,  it  may  be  advantageous  to  furnish  one 
or  more  of  the  windows  with  some  form  of  the  diffusing 
and  refracting  prisms  already  described  (page  298),  thus 
giving  an  abundance  of  light  where  there  was  formerly  a 
deficiency,  and  materially  lessening  the  eye-strain  of  the 
scholars. 

Basements  of  school-houses  should  be  well  lighted  and 
dry,  and  should  be  kept  scrupulously  clean  that  moisture 
and  noxious  gases  may  not  be  drawn  into  the  rooms  above. 
If  properly  arranged  and  cared  for,  they  may  be  used  as 
play-rooms  in  stormy  weather  when  it  would  be  unwise  to 
send  the  scholars  out-of-doors. 

The  water-supply  should  be  free  from  impurities  and  as 
good  as  can  be  had.  In  the  country,  if  from  a  neighbor- 
ing farm-house  spring  or  well,  it  may  be  contaminated  by 
leakage  from  cesspools  and  barnyards.  Or  the  school 
water  may  be  taken  from  a  neighboring  spring  or  stream 
which  is  receiving  contamination  from  the  school-house 
cesspool  or  other  .sources.  For  this  reason,  teachers 
should  be  taught  the  tests  for  chlorides  and  ammonia  and 
the  reason  for  making  them,  and  should  make  these  tests 
frequently.  If  cause  for  suspicion  arises,  the  use  of  the 
water  should  be  stopped  at  once. 

21 


322  SCHOOL  HYGIENE. 

Water-closets  and  urinals,  where  in  use,  should  be  kept 
clean  by  a  competent  janitor,  and  the  principal  or  bead- 
teacher  should  see  that  this  is  done.  In  the  country,  the 
pail  or  earth-closet  system  should  be  substituted  for  the 
usual  privy-vault  or  cesspool,  and  it  should  be  the  duty 
of  some  one  apart  from  the  teacher,  regularly  appointed 
and  paid  by  the  school  directors  of  the  district,  to  see  that 
removals  are  made  at  proper  intervals ;  the  teacher  should 
maintain  supervision  over  the  daily  condition  of  affairs. 
If  possible,  the  out-houses  should  be  connected  with  the 
school-house  by  covered  ways,  that  the  children  may  not 
be  exposed  in  inclement  weather ;  but  these  ways  should 
be  open  or  else  constantly  ventilated  by  open  windows  on 
either  side.  Cesspools,  if  unavoidable,  should  be  at  least 
fifty  feet  distant,  and  should  drain  away  from  the  school- 
house. 

Though  approving  the  Smead  system  of  warming  and 
ventilation  for  school-rooms,  the  writer  cannot  say  that 
he  approves  that  modification  of  it  wherein  the  foul  air 
from  the  building  is  carried  over  the  fecal  excreta  of  the 
inmates  before  being  discharged  into  the  outlet  shafts  and 
carried  to  the  outer  air.  Though  the  method  rapidly 
desiccates  the  excreta  and  renders  it  inoffensive  to  the 
senses,  there  is  danger  of  the  dissemination  of  disease 
germs  as  well  as  a  departure  from  sanitary  principles  in 
the  method. 

Ample  provision  must  be  made  for  the  rapid  escape 
and  for  the  safety  of  scholars  and  teachers  in  case  of  fire 
or  panic.  Fire-drills  should  be  regularly  practised  in 
all  schools  of  two  stories  or  more,  and  presence  of  mind 
inculcated,  that  emergencies  may  be  met  with  safety. 
The  comfort  of  the  child  should  not  be  forgotten  in  the 


SCHOOL   QUARANTINE.  323 

construction  of  the  school-house,  though  preservation  of 
health  is  the  main  aim. 

School  Quarantine. — As  certain  diseases  are  conta- 
gious, it  is  necessary  that  school  authorities  have  the  right 
to  forbid  the  attendance  of  such  persons  as  have  been  ex- 
posed to  infection  until  all  danger  of  transmitting  the  dis- 
ease to  others  is  passed.  This  power  is  usually,  however, 
exerted  only  in  the  case  of  those  diseases  most  dangerous 
to  life  and  health,  though  the  stringency  of  the  regulations 
varies  at  different  places.  Smallpox,  scarlet  fever,  diph- 
theria, measles,  and  even  whooping-cough  should  always 
be  quarantined,  and  it  would  be  better  to  keep  children 
who  are  afflicted  with  minor  diseases  of  this  class  out  of 
school  till  all  danger  of  infection  is  over,  as  it  is  only  by 
rigid  measures  like  this  that  we  may  finally  be  able  to 
eradicate  those  maladies.  Considerable  evidence  now  sup- 
ports the  view  that  there  is  a  marked  decrease  in  the  prev- 
alence of  both  scarlet  fever  and  diphtheria  during  the 
summer  holidays  and  an  increase  due  to  school  attendance. 
But  Niven,  of  Manchester,  England,  thinks  that  "  the 
extreme  measure  of  closing  a  school  for  scarlet  fever  is 
rarely  called  for,  and  is  not  so  likely  to  be  effectual  as  in 
the  case  of  measles."  ^ 

Local  boards  of  health  should  make  and  enforce 
rules  looking  to  the  prevention  of  the  spread  of  the 
graver  contagious  diseases,  and  should,  when  necessary, 
close  school-buildings  till  all  danger  is  past.  Lincoln 
gives  the  following  as  a  system  of  general  regulations : 
"1.  Persons  affected  with  diphtheria,  measles,  scarlet 
fever,  or  smallpox  (varioloid)  must  be  excluded  from  the 

1  See  Public  Health,  February,  June,  and  September,  1899;  also, 
American  Year-book  of  Medicine  for  1900,  p.  538. 


324  SCHOOL  HYGIENE. 

schools  until  official  permission  is  given  by  the  board 
of  health  for  their  readmission.  2.  Persons  living  in  a 
family  or  house  where  such  a  case  occurs  are  also  excluded 
until  similar  permission  is  given.  3.  This  permission  is 
not  to  be  given  until  sufficient  time  has  elapsed  since  the 
occurrence  of  the  last  case  to  insure  safety,  nor  until  the 
premises  have  been  disinfected  under  the  direction  of  the 
board  of  health.  4.  If  a  child  suffering  from  one  of  the 
above  diseases  attends  school,  the  premises  of  the  school 
must  be  disinfected  under  the  direction  of  the  board  of 
health  before  they  are  used  again.  5.  Physicians,  teachers, 
school  officers,  and  school  children  knowing  of  such  cases 
of  disease  should  at  once  report  them  to  the  board  of 
health.  6.  The  board  should  also  notify  the  school 
authorities  of  all  such  cases.  7.  Notice  must  be  sent  to 
the  family  by  the  school  authorities,  acting  conjointly 
with  the  board  of  health." 

In  Indianapolis  a  card  catalogue  is  kept  of  all  the 
pupils  in  the  public  schools,  each  card  representing  a 
single  pupil  and  giving  full  information  concerning  his 
or  lier  home,  parents,  brothers  and  sisters,  and  where  the 
same  are  employed,  or  are  attending  school.  In  case  of 
the  absence  of  any  pupil  for  three  days  or  more,  the  city 
board  of  health  must  be  notified  by  the  school  authorities 
and  the  scholar  is  not  permitted  to  return  to  school  until 
the  health  officers  are  satisfied  that  there  is  no  danger  of 
info(!tion  and  have  so  notified  those  in  charge  of  the 
school. 

The  following  tal)lc  of  the  ])criods  of  incubation  of  the 
respective  diseases  is  based  on  an  experience  of  over 
twenty-eight  years  at  the  Rugby  School,  England,  by 
Clement  Dukes.^ 

»  l,ancct,  April  29,  1899. 


PERIODS  OF  INCUBATION, 


325 


An  Analysis  of  the  Periods  of  Incubation. 


Name  of 
disease. 

Short- 
est 
period 
of  incu- 
bation 
(days). 

Long- 
est 
period 
of  incu- 
bation 
(days). 

The  largest 

number 

occur  on  tlie 

following 

days. 

The  majority  of 

the  cases  arise 

between  the 

following  days. 

Percentage  re- 
ferring to  pre- 
vious column, 
e.  g.,  59  per  ct. 
occur  between 
the  second  and 
fourth  days. 

Scarlet  fever     . 
Chickenpox  .   . 
JInmps   .... 
Rose-rash  .   .   . 
Measles  .... 

1 

13 
14 
12 

8 

9 
19 
25 
22 
14 

Second  and 

fourth 
Fifteenth 

Nineteenth 

Sixteenth 

Eleventh 

Second  and 

fourth 
Fourteenth  and 

seventeenth 
Seventeenth  and 

twentieth 
Fourteenth  and 

seventeenth 
Ninth  and 

twelfth 

10  out  of  17  = 

59  per  cent. 
24  out  of  36  = 

66  per  cent. 
50  out  of  69  = 

72.46  per  ct. 
31  out  of  40  = 

77.50  per  ct. 
18  out  of  24  = 

75  per  cent. 

Another  authority  gives  the  following : 

Table  of  the  Eruptive  Fevers. 


Name. 

Incubation. 

Day  of  rash. 

Duration  of 
eruption. 

Duration  of 
disease. 

Chickenpox 
Erysipelas 
Measles    . 

4  to  14  days 

1  to    5  days 

10  to  12  days 

7  to  17  days 
1  to  21  days 

8  to  14  days 
10  to  21  days 

Second  or  third 
First  to  third 
Fourth 

First  or  second 
Second 

Third  or  fourth 
Seventh  to  four- 
teenth 

4  to    8  days 
4  to    8  days 
3  to    5  days 
1  to    3  days 
4  to  10  days 
16  to  25  days 

1  to    2  weeks 
1  to    3  weeks 
10  to  14  days 

Scarlatinal 

2  to    3  weeks 

3  to   5  weeks 

Typhoid  fever    .   . 

3  to   4  weeks 

Children  having  had  one  of  the  above-named  diseases 
may  return  to  school  with  safety  after  the  following 
periods,  provided  there  has  been  a  thorough  disinfection 
of  their  homes  and  clothing:  "Scarlet  fever,  six  weeks 
from  the  date  of  rash,  provided  desquamation  and  cough 
have  ceased.  Smallpox  and  chickenpox,  when  every  scab 
has  fallen.     Whooping-cough,  after  six  weeks  from  com- 

1  In  regard  to  the  discrepancy  in  the  above  tables  respecting  the 
incubation  of  scarlet  fever  (from  one  to  twenty-one  days)  the  writer 
believes  the  shorter  period  to  be  more  nearly  correct;  also  that  the 
incubation  period  of  measles  is  frequently  less  than  ten  days,  as  is  occa- 
sionally that  of  typhoid  fever.  Eelapses  may  extend  the  duration  of 
typhoid  fever  to  much  more  than  four  weeks. 


326  SCHOOL  HYGIEXE. 

mencement  of  whoopino-^  providing  tlie  characteristic  spas- 
modic cough  and  M-hooping  have  ceased,  or  earlier  if  all 
cough  have  passed  an-ay.  Diphtheria,  not  less  than  three 
weeks,  if  convalescence  is  completed ;  there  being  no 
longer  any  form  of  sore  throat  nor  any  kind  of  dis- 
charge from  the  throat,  nose,  eyes,  ears,  etc.,  nor  any 
alluiminuria."  Wherever  possible,  a  bacteriological  ex- 
amination of  the  nose  and  throat  secretions  of  a  scholar 
that  has  had  diphtheria  should  be  made  from  time  to 
time,  and  his  return  to  school  should  only  be  permitted 
when  two  examinations  no  longer  show  the  presence 
of  the  specific  organism  in  the  secretions  mentioned. 
Rules  and  regulations  like  the  above,  when  promulgated, 
"  should  have  the  force  and  authority  of  law,  and  should 
be  enforced,  if  necessary,  by  the  entire  power,  including 
school  officers,  etc.,  of  the  State." 

Boarding-schools  and  similar  institutions  should  have 
an  infirmary  where  contagious  diseases  may  be  isolated, 
and  those  in  charge  should  make  that  isolation  from  other 
scholars  and  inmates  as  complete  as  possible.  At  the 
beginning  of  a  term  it  may  be  well  to  subject  scholars 
who  have  been  exposed  to  contagion  to  a  postjjonement 
of  attendance  until  the  probable  period  of  incubation  for 
the  special  disease  is  passed,  the  period  dating  from  the 
time  of  exposure  and  sul)sequent  disinfection  of  clothing, 
etc.  With  the  above  precautions  it  will  rarely  be  neces- 
sarv  to  close  a  scliool  unless  a  disease  is  markedly  epi- 
demic and  malignant. 

1  Recent  investigations  have  shown  that  the  purulent  discharge  from 
the  car  that  so  often  follows  attacks  of  measles  and  scarlet-fever,  and, 
less  frequently,  of  diphtheria,  may  be  highly  infectious  and  a  positive 
agent  in  disseminating  the  respective  maladies.  Consequently  children 
should  he  excluded  from  schools  untiUhis  sequel  of  disease  as  well  as 
others  has  entirely  disappeared. 


VACCINATION  OF  SCHOOL   CHILDREN.         327 

It  is  to  be  hoped  that  we  shall  soon  have  a  means  of 
inoculating  persons  against  all  contagious  diseases,  as  we 
now  do  against  smallpox.  At  present,  boards  of  health 
and  school  boards  should  insist  on  the  vaccination  of  all 
school  children.  In  Illinois,  from  1880  to  1883,  the 
deaths  from  smallpox  among  unvaccinated  children  were 
48  per  cent,  of  those  incurring  the  disease;  among  the 
vaccinated,  only  0.9  per  cent.  In  Philadelphia  all  who 
desire  it  are  vaccinated  free  of  charge  by  the  vaccine 
physicians,  and  it  is  compulsory  for  all  school  children. 

Lincoln  has  also  suggested  that  further  regulations 
similar  to  the  following  should  be  in  force  in  every  school 
district :  "  Every  child  entering  the  public  schools  must 
show  a  certificate  from  some  reputable  physician,  giving 
name,  age,  residence,  approximate  date  of  vaccination, 
date  of  examination,  result  of  examination,  the  last  two 
to  be  of  the  physician's  own  knowledge.  The  fact  of 
vaccination  must  be  entered  on  the  school  record  and  on 
lists  for  promotion  and  transfer.  The  school  authorities 
shall  annually  report  the  number  of  those  not  protected 
to  the  State  Superintendent  of  Education.  School  author- 
ities may  order  the  exclusion  of  non-protected  persons, 
after  sufficient  notice,  where  they  think  the  measure  re- 
quired for  the  public  health.  Re-vaccination  at  the  age 
of  fifteen  may  be  required  under  similar  circumstances. 
Those  unable  to  pay  should  be  furnished  with  free  vac- 
ciuatlon  by  the  school  authorities.  A  physician's  cer- 
tificate of  protection  by  a  jjrevious  attack  of  smallpox  is 
equivalent  to  a  certificate  of  vaccination." 

Contagious  ophthalmia  is  a  disease  often  prevalent  in 
charitable  and  educational  institutions  and  occasionally 
in  primary  schools,  and  requires  great  care  to  prevent  its 
iiivasion  and  spreading,  as  well  as  to  effect  a  cure.     Those 


328  SCHOOL  HYGIENE. 

afflicted  with  it  should  be  quarantined  until  there  is  no 
further  discharge  or  till  the  granulations  on  the  inner 
surface  of  the  eyelids  have  disappeared.  Enfeebled  health 
and  poor  and  insufficient  food  favor  its  development,  but 
the  chief  means  of  contagion  is  by  the  use  of  the  same 
wash-basins  and  towels  by  a  number  of  children. 

Other  diseases  that  may  be  transmitted  in  much  the 
same  way  are  chronic  conjunctivitis  ("  granular  lids ") 
and  those  due  to  fungous  and  other  parasites,  as  the  tineas 
("  ringworm  of  the  scalp  or  face "),  pediculosis,  etc.,  all 
of  which  may  be  transmitted  by  an  interchange  of  hats  or 
caps  or  other  garments. 
%  School  children   should  not  be  allowed  to  attend  the 

funerals  of  companions  dead  of  a  contagious  disease,  nor 
should  funerals  be  allowed  to  take  place  from  school- 
houses  under  any  circumstance,  owing  to  the  eifect  on 
the  thoughts  and  sensibilities  of  nervous  children. 


CHAPTER    X. 

DISINFECTION. 

As  has  been  stated,  disinfection  is  that  part  of  pro- 
phylaxis which  has  to  do  with  the  destruction  or  modifi- 
cation of  the  exciting  causes  of  disease,  and  we  may 
accordingly  define  a  disinfectant  as  "  an  agent  capable  of 
destroying  the  infective  power  of  infectious  material,"  or, 
as  "  an  agent  which  brings  about  the  destruction  of  bac- 
teria in  general,  and  more  particularly  of  those  that  act 
as  the  exciting  causes  of  disease."  ^  Consequently,  as  with 
our  present  knowledge  we  are  practically  limited  in  the 
use  of  disinfection  to  the  infectious  diseases  only,  a  disin- 
fectant must  also  be  a  germicide.  Theoretically,  it  should 
also  have  the  power  of  destroying  the  poisonous  proper- 
ties of  the  toxins  which  the  disease  germs  produce,  and 
which  create  the  characteristic  symptoms  of  the  specific 
diseases ;  but  whether  all  efficient  disinfectants  have  this 
power  is  by  no  means  proved  ;  nor  is  it  altogether  essen- 
tial that  they  do  have  it,  since  by  killing  the  germs  we 
check  the  further  production  of  the  toxins ;  and  disinfec- 
tants are  mainly  used  not  so  much  to  cure  or  arrest  the 
progress  of  a  disease  in  a  patient  as  to  prevent  its  incur- 
rence by  others.  But,  in  a  popular  sense,  the  term  dis- 
infection is  given  a  wider  meaning  than  is  indicated 
above,  including  not  only  the  use  of  antiseptics  and 
deodorants,  but  also  often  the  actual  removal  of  filth 
and  all  matters  favorable  to  the  growth  or  spread  of 

1  Harrington,  Practical  Hygiene,  p.  488. 

329 


330  DISINFECTION. 

disease  germs,  which  is,  strictly  speaking,  a  matter  of 
sanitation.  It  is  needless  to  say  that  the  latter  work  may 
be  part  of  the  prescribed  duties  of  a  disinfector,  but  it  is 
not  one  of  the  essential  functions  of  a  disinfectant. 

It  will  be  well  here  to  make  the  distinction  between 
disinfectants  and  antiseptics  and  deodorants,  as  the  terms 
are  often  wrongly  used  interchangeably,  and  there  is  a 
common  belief  that  whatever  is  a  deodorant  or  an  anti- 
septic is  also  a  disinfectant.  An  aniiseptiG  is  an  agent 
that  retards  or  arrests  bacterial  growth  and  the  conse- 
quent production  of  toxins  or  ptomains,  though  it  does 
not  necessarily  kill  the  micro-organisms  themselves ;  and 
though  some  antiseptics  are  germicidal,  others  are  not, 
and  therefore  as  a  class  they  cannot  be  considered  or 
used  as  disinfectants.  But,  on  the  other  hand,  "  agents 
which  kill  bacteria  in  a  certain  amount  prevent  the  mul- 
tiplication of  the  latter  in  culture-fluids  when  present  in 
quantities  considerably  less  than  are  required  to  destroy 
vitality."  So,  a  diluted  germicide  may  act  as  an  anti- 
septic and  may  be  used  therefor.  For  instance,  chlorin- 
ated lime,  which  is  a  good  disinfectant  in  solutions  of 
proper  strength,  may  arrest  further  bacterial  growth  or 
action  in  a  mass  of  sewage  or  filth  and  prevent  the  latter 
acting  as  a  culture-medium  for  disease  germs,  even 
tliough  the  agent  be  totally  inadequate  in  quantity  to  kill 
all  the  micro-organisms  present.  In  the  same  way,  it 
may  act  as  a  deodorant — which,  by  the  way,  is  an  agent 
that  sim])ly  removes  or  destroys  offensive  odors,  and  is 
not  necessarily  either  a  disinfectant  or  an  antiseptic---both 
by  checking  the  further  action  of  saprophytic  bacteria 
and  the  consequent  formation  of  putrefactive  odors,  and 
by  actually  decomposing  and  oxidizing  those  of  the  latter 
already  formed. 


THOROUGHNESS  IN  DISINFECTION  ESSENTIAL.  331 

In  practical  disinfection  it  is  also  well  to  remember 
that  while  masses  of  dead  organic  matter  may  not  in  some 
cases  contain  disease  germs,  and  may  be  even  hostile  to 
them,  in  general  the  reverse  of  this  is  more  likely  to  be 
true,  and  decaying  matter  often  furnishes  a  good  field  for 
the  increase  of  pathogenic  organisms.  Moreover,  the 
noxious  gases  given  oif  to  the  air  and  the  poisonous 
products  added  to  a  drinking-water  from  such  masses 
may  also  do  much  harm  by  depressing  the  system,  lower- 
ing the  vitality,  and  acting  as  predisposing  conditions  to 
the  incurrence  of  such  filth  diseases  as  cholera,  yellow 
fever,  typhoid  and  typhus  fever,  diphtheria,  etc. ;  and 
when  time  or  opportunity  does  not  permit  of  the  removal 
of  such  dangerous  accumulations,  their  power  for  harm 
should  be  checked  permanently  or,  at  least,  temporarily 
by  the  use  of  suitable  disinfectants  or  antiseptics. 

But  when  we  are  actually  dealing  with  disease  germs, 
disinfection,  to  be  trustworthy,  must  be  carried  out  to 
the  best  of  our  ability  with  the  means  at  our  command 
and  with  strict  attention  to  the  minutest  details.  "  There 
can  be  no  partial  disinfection  of  infectious  material ; 
either  its  infectious  power  is  destroyed  or  it  is  not.  In 
the  latter  case  there  is  a  failure  to  disinfect."  This  is 
because  the  undestroyed  living  bacteria  still  have  the 
power  of  reproduction,  and  may,  within  a  very  short  time 
imder  favorable  circumstances,  equal  or  even  exceed  the 
number  that  was  present  before  the  unsuccessful  attempt 
at  disinfection  was  made.  In  fact,  our  aim  in  such  pro- 
phylaxis must  always  be  "  to  interrupt  all  possible  paths 
of  disease  conveyance,  and  to  exterminate  the  causal 
agent." 

The  knowledge  as  to  the  efficacy  of  any  substance  as  a 
disinfectant  is  obtained  from  the  accumulated  experiences 


332  DISINFECTION. 

of  practical  sanitarians  and  from  experiments  on  suscep- 
tible animals  and  in  culture-media  in  which  infectious 
matter  is  treated  with  the  substance  in  question  or  that  is 
being  tested.  The  knowledge  gained  must  stand  the  test 
of  scientific  deduction,  and  a  substance  is  not  a  disinfect- 
ant simply  because,  in  one  given  case,  infection  did  not 
occur  after  its  use.  To  be  of  value  the  deductions  must 
be  made  from  considerable  accumulated  and  practical 
experience.  "  Negative  evidence  should  be  received  with 
great  caution;"  but  if  the  experience  of  practical  sanita- 
rians is  confirmed  by  careful  culture  and  inoculation 
experiments,  our  knowledge  of  the  value  of  any  agent 
becomes  more  definite  and  our  practical  work  more  exact. 
From  such  inoculations  and  experiments  it  has  been 
found  that  the  infectious  germs  of  different  diseases  differ 
in  their  power  to  resist  the  different  disinfectants ;  but 
nevertheless  it  may  be  stated  that  "  in  the  absence  of 
spores,  a  disinfectant  for  one  is  a  disinfectant  for  all." 
Consequently,  we  are  able  to  simplify  and  classify  the 
agents  at  our  disposal  and  to  make  more  effectual  use  of 
them.  Note  that  there  is  nothing  in  the  tests  mentioned 
that  tends  to  disprove  the  efficacy  of  disinfectants,  what- 
ever the  nature  of  the  infecting  material  and  whether  the 
germ  theory  be  accepted  or  not. 

Some  agents  that  are  powerful  against  all  other  organ- 
isms completely  fail  to  destroy  the  vitality  of  spores, 
and  thus  our  list  of  disinfectants  available  in  all  cases  is 
still  further  reduced.  In  the  case  of  a  disease  germ  that 
do(!s  not  produce  spores,  as  that  of  cholera,  and  probably 
also  of  scarlet  fever,  smallpox,  yellow  fever,  etc.,  agents 
may  be  used  that  are  powerless  against  spores,  but  in 
doulitful  cases  only  those  should  be  used  that  have  the 
power  of  spore  destruction. 


CLASSIFICATION  OF  DISINFECTANTS.  333 

We  may  classify  tlie  disiufectants  of  which  we  may 
make  practical  use  as  either  thermal  or  chemical,  though 
there  are  undoubtedly  certain  secretions  and  tissues  in  the 
body  which  have  the  power  of  destroying  infective  mat- 
ters, giving  each  person  more  or  less  immunity  against 
certain  diseases,  and  these  we  may  term  physiological 
disinfectants. 

There  may  also  be  a  mechanical  sterilization,  as  in  the 
separation  of  micro-organisms  from  a  liquid  by  filtration 
or  sedimentation,  or  by  their  physical  removal  from  very 
smooth  articles  by  wiping,  or  from  the  human  skin  by 
thorough  scrubbing  and  washing.  AYhether  the  latter 
may  prove  efficient  depends  on  the  smoothness  of  the 
person's  skin,  his  exposure  to  pathogenic  germs,  and  espe- 
cially upon  the  care  and  thoroughness  with  which  the 
cleansing  process  is  accomplished. 

Thermal  Disinfectants. — Of  the  thermal  disinfectants, 
fire  is  the  most  efficacious,  as  it  destroys  all  organic  mat- 
ter, but  it  can  only  be  used  to  disinfect  non-combustible 
articles  or  those  that  are  of  little  value  and  that  cannot  be 
safely  disinfected  in  any  other  way.  For  instance,  as  it 
will  usually  cost  more  than  they  are  worth  to  disinfect 
thoroughly  by  other  methods  old  mattresses  that  have 
been  used  in  an  infectious  case,  it  is  best  to  burn  them. 

All  things  considered,  steam  is  probably  the  most  prac- 
tically efficient  disinfectant,  as  it  is  cheap,  easily  used  and 
manipulated,  and  is  less  liable  to  injure  the  articles  to  be 
disinfected.  We  employ  it  under  pressure,  when  its  tem- 
perature is  correspondingly  increased,  or  in  the  streaming 
state  (live  steam),  the  latter  being  as  efficient  as  the 
former,  but  sometimes  requiring  a  little  longer  time.  For 
instance,  steam  at  240°  F.  is  said  to  kill  the  most  resistant 
spores  very  quickly,  and  streaming  steam  at  212°  F.  will 


334 


DISINFECTION. 


produce  the  same  eiiect  within  thirty  or  forty  minutes. 
In  fact,  under  very  favorable  conditions,  probably  few,  if 
any,  of  the  ordinary  pathogens  can  withstand  the  tem- 
perature of  boiling  water  (212°  F.)  longer  than  a  few 
minutes,  but  it  is  always  wise  to  employ  sufficient  time 
and  heat  to  remove  any  possibility  of  doubt  or  danger. 
One  should  also  remember  that  for  surface  disinfection 
streaming  saturated  steam  is  relatively  much  more  efficient 

Fig.  57. 


Steam  sterilizer  for  small  articles. 

than  superheated  steam,  on  account  of  the  great  liberation 
of  latent  heat  when  the  former  condenses,  and  ])ossibly 
because  the  latter  tends  to  dry  rather  than  moisten  the 
organisms  and  thus  render  them  harder  to  disinfect.  Spe- 
cial a]i})aratus  for  disinfecting  large  articles  by  steam  is 
now  or  d()ul)tlcss  .'^oon  will  be  established  in  every  large 
city  and  hospital  ])y  (he  mnnieijial  authorities  and  others, 
as  a  sanitary  jjrecaution  and  to  prevent  the  spread  of 
epidemics. 


STEAM  DISINFECTION. 


335 


In  steam  sterilization,  as  with  all  other  disinfectants, 
the  aim  must  be  to  bring  the  germicidal  agent  into  contact 
with  every  part  of  the  infected  matter;  in  other  words, 
to  secure  thorough  penetration.  The  size  and  compact- 
ness of  the  articles  to  be  sterilized  accordingly  govern  in 
part  the  duration  of  their  treatment  by  the  steam.  Steam 
under  pressure  is,  of  course,  more  penetrating  than  live 
steam,  and  is  especially  expeditious  when  the  apparatus 

Fig.  58. 


Steam  disinfecting  chamber  for  clothing,  bedding,  and  other  large  articles. 

is  so  arranged  that  the  air  can  be  exhausted  from  it  and 
a  vacuum  created  in  the  interstices  of  the  articles  to  be 
disinfected  before  the  steam  is  introduced. 

In  the  large  sterilizers  constructed  for  hospital  or  mu- 
nicipal use  every  precaution  is  taken  to  prevent  the  rein- 
fection of  articles  after  they  have  been  once  sterilized.  The 
goods  enter  the  apparatus  at  one  end,  and  after  the  treat- 
ment are  taken  from  it  at  the  other  end,  being  handled 


336  DISINFECTION. 

and  delivered  to  their  owners  or  destination  by  an  entirely 
different  group  of  employes  and  conveyances  than  those 
concerned  with  them  before  the  disinfection.  The  appa- 
ratus is  built  into  a  closed  partition,  which  entirely  sepa- 
rates the  two  parts  of  the  disinfecting  building  and  pre- 
vents any  transmission  of  germs  from  the  infected  to  the 
disinfected  side,  especially  as  the  doors  of  the  sterilizer 
are,  or  should  be,  so  arranged  that  they  cannot  both  be 
open  at  the  same  time. 

Boiling-point  of  Water  under  Steam-pressure.^ 

Steam-pressure  Boiling  tempei-ature. 

(pounds).  (F.)  (C.) 

0 .    .  212°  100.0° 

5 228°  109.0° 

10 240°  115.5° 

15 251°  121.5° 

20 260°  126.5° 

40 287°  141.5° 

In  the  absence  of  spores,  bacteria  are  killed  by  hot 
water  even  below  the  boiling-point,  and  it  is  safe  to  say 
that  boiling  for  ten  or  fifteen  minutes  will  kill  all  known 
disease  germs,  especially  if  from  1  to  2  per  cent,  of  wash- 
ing soda  or  a  little  common  salt  (sodium  chloride)  be 
added  to  the  water ;  although  sjjores  of  certain  harmless 
bacilli  are  said  to  have  resisted  boiling  for  several  hours. 
The  addition  of  soda  also  prevents  the  rusting  of  iron  or 
steel  instruments,  but  is  likely  to  cause  erosion  of  alumi- 
num articles.  In  the  absence  f)f  chemical  disinfectants, 
boiling  water  may  be  used  to  disinfect  excreta,  etc. ;  and 
all  clothing  worn  by  the  sick  or  the  attendants  upon  the 
sick  .should  be  well  boiled  before  using  again,  whether 
other  disinfectants  are  employed  or  not. 

^  McFarland  and  Babcock,  in  Cohen's  System  of  Physiologic  Thera- 
peutics, vol.  v.,  p.  201. 


DISINFECTION  BY  DRY  HEAT.  337 

Dry  heat  is  far  less  penetrating  and  less  effective  than 
moist,  and  must  accordingly  be  used  at  much  higher 
temperatures  and  for  a  longer  time.  At  300°  F.  dry  air 
■will  require  at  least  three  or  four  times  as  long  to  do  what 
steam  at  212°  or  220°  F.  will  do,  and,  moreover,  it  is 
very  apt  to  injure  clothing  or  other  organic  materials  ex- 
posed to  it  at  such  high  temperatures  for  so  long  a  time 
as  is  necessary.  Consequently,  it  is  only  to  be  used  to 
disinfect  articles  that  would  be  spoiled  by  moisture  or 
chemicals,  and  even  then  it  is  better  to  employ  the  "  frac- 
tional" method  of  disinfection — i.  e.,  exposure  to  high 
temperatures  for  short  periods  only,  but  for  a  number  of 
times,  with  sufficient  intervals  between  the  exposures  to 
allow  the  development  of  any  spores  that  may  possibly  be 
present. 

Contrary  to  the  popular  opinion,  cold  is  not  a  positive 
germicide,  or  at  best  is  but  a  slowly  acting  one.  Typhoid 
germs  have  been  frozen  for  more  than  one  hundred  days 
without  losing  their  power  for  harm,  and  various  micro- 
organisms have  withstood  the  temperature  of  liquid  air — ■ 
below  — 300°  F. — for  several  hours  or  days.  However, 
freezing,  especially  if  intermittent,  is  harmful  to  the  growth 
of  bacteria,  and  they  gradually  decrease  in  number  in  frozen 
material. 

In  this  connection  it  Is  not  out  of  place  to  refer  again 
to  the  germicidal  power  of  light,  especially  sunlight,  and 
to  its  value  as  an  adjunct  in  the  disinfecting  of  rooms, 
clothing,  etc.  It  is  an  agent  that  may  be  used  progressively 
and  efficiently  in  the  sick-room  throughout  the  course  of 
an  infectious  disease  ;  and  psychically,  as  well  as  other- 
wise, adds  to  the  cheer  and  comfort  of  the  patient  rather 
tlian  to  increase  his  discomfort,  as  does  the  use  of  most 
other  means  to  the  same  end. 
22 


338  DISINFECTION. 

Chemical    Disinfectants. — Regarding    the    chemical 

disinft'ctants,  it  must  be  remembered  that  it  requires  a 
eertuin  amount  of  each  to  disinfect  a  given  quantity  of 
bacteria,  and  also  that,  with  all  disinfectants,  time  is  an 
important  element,  as  none  act  absolutely  instantaneously. 
Heat,  however,  facilitates  and  increases  the  rapidity  of 
action  of  the  chemical  disinfectants. 

Another  caution  to  be  observed  is  that  the  disinfectant 
should  always  be  of  sufficient  strength  in  the  mixture  with 
infected  material.  For  example,  if  a  disinfectant  is  only 
eifective  in  1  per  cent,  strength  or  more,  then  at  least  a 
2  per  cent,  solution  should  be  added,  volume  for  volume, 
to  the  matters  to  be  disinfected,  and  should  be  thoroughly 
mixed  with  the  latter  in  order  that  the  germicide  may  be 
brought  into  contact  with  all  the  infective  organisms. 

Chlorinated  lime  (often  called  chloride  of  lime)  is  one 
of  the  best  and  cheapest  disinfectants.  It  should  contain 
at  least  35  per  cent,  of  available  chlorine,  should  be  kept 
covered  from  air  and  moisture,  and  fresh  solutions  should 
always  be  made  as  needed.  Its  power  is  due  to  hypo- 
chlorite of  lime,  which  is  freely  soluble  in  water  and 
readily  decomposes  in  contact  with  organic  matter,  giving 
up  chlorine  gas — a  most  powerful  disinfectant.  "  Germs 
of  all  kinds,  including  the  most  resistant  spores,  are 
destroyed  by  this  solution  ;  but  it  must  be  remembered 
that  the  disinfectant  itself  is  quickly  decomposed  and 
destroyed  by  contact  with  organic  matter,  and  that  if  this 
is  present  in  excess,  disinfection  may  not  be  accomplished, 
especially  when  the  germs  are  embedded  in  masses  of 
material  which  are  left  unacted  upon  after  the  hypochlo- 
rite of  lime  has  been  all  exhausted  in  the  solution."  La- 
barrafjue's  solution  of  chlorinated  soda  is  a  very  mild 
disinfectant,  but  does  not  keep  well,  and  chlorinated  lime 


CHEMICAL  DISINFECTANTS.  339 

is  equally  as  good  and  much  cheaper.  However,  the  soda 
solution  has  scarcely  any  disagreeable  odor,  and  makes  a 
pleasant  disinfecting  bath  for  the  person.  The  official 
solution  must  contain  at  least  3  per  cent,  of  available  chlo- 
rine, but  it  may  be  diluted  with  from  two  to  five  parts  of 
water  before  use,  especially  for  bathing. 

Though  probably  effective  against  sporeless  bacteria  in 
somewhat  less  proportions,  solutions  of  chlorinated  lime 
should  be  of  at  least  1  per  cent,  strength  by  weight,  and 
should  be  used  in  excess,  rtcJ  ,allow  for  both  the  dilution  by 
the  mass  to  be  disinfected  aioidot^e  exhaustion  of  the  hypo- 
chlorite by  organic  matter. 

Bichloride  of  mercury  As  one  of  the  best  germicides  that 
we  have,  and  is  effective  in, .comparatively  weak  solutions. 
It  corrodes  metal,  and  so  cannot  be  used  to  disinfect  waste- 
pipes,  etc. ;  and  it  combines  with  and  coagulates  albumin, 
which  interferes  somewhat  with  its  action.  This  coagu- 
lation is  prevented  to  a  degree  by  the  addition  of  a 
small  amount  of  citric  or  tartaric  acid  or  of  ammonium 
chloride  to  the  disinfecting  liquid.  The  same  result  is 
said  to  be  obtained  if  one  part  of  hydrogen  peroxide 
(15  per  cent,  solution)  be  added  to  three  parts  of  a  cor- 
rosive sublimate  solution  of  any  strength,  or  by  adding 
common  salt  (0.5  to  1  per  cent.)  to  the  solution.  But  for 
the  above  reason  it  is  better  not  to  use  corrosive  sublimate 
in  disinfecting  fecal  excreta  or  sputum,  as  these  always 
contain  more  or  less  albumin,  and  also  because  the  sulphur 
present  in  the  excreta  permits  the  formation  of  a  sulphide 
of  mercury,  which  has  almost  no  power  as  a  disinfectant. 
A  lime  solution  is  better  and  more  certain. 

Bichloride  of  mercury  should  be  used  in  solutions  of 
from  1  in  1000  to  1  in  500  strength  for  ordinary  disin- 
fection, though  weaker  preparations  are  sometimes  used 


340  DISINFECTION. 

ill  surgical  cases.  It  is  especially  valuable  where  a  large 
amount  of  fluid  is  to  be  freely  used,  but  the  solutions 
should  always  be  colored  by  a  little  aniline  dye  or  copper 
sulphate,  on  account  of  its  poisonous  properties,  and  the 
consequent  danger  from  its  lack  of  color.  Abbott  cau- 
tions that  the  stains  of  blood  and  feces  on  clothing;  are 
rendered  almost  indelible  by  long  soaking  in  bichloride 
solutions.  Silver  nitrate  is  almost,  if  not  fully,  as  good 
a  disinfectant  as  bichloride  of  mercury,  and  does  not 
coagulate  albumin  so  readilyi,  biit  is  much  more  expensive. 

Carbolic  acid  is  effectik^eli^'the  absence  of  spores,  and, 
according  to  Koch,  should  have  first  place  in  disinfection 
against  the  cholera  germ.  It  is\  of  doubtful  value,  how- 
ever, in  cases  of  typhoid  fever,  as  it  is  said  that  the 
typhoid  bacilli  can  be  cultivated  in  a  medium  containing 
0.5  per  cent,  of  carbolic  acid.  SMutions  should  always  be 
made  by  first  dissolving  the  acid  in  hot  water,  and  should 
contain  from  2  to  5  per  cent,  of  acid,  the  latter  being 
practically  a  saturated  solution.  The  stronger  solution  is 
especially  valuable  for  the  direct  disinfection  of  human 
excreta  of  all  kinds,  but  must  be  thoroughly  mixed  with 
the  same,  as  carbolic  acid  coagulates  albumin  somewhat, 
while  the  weaker  fluid  (2  or  3  per  cent.)  may  be  used 
freely  for  the  disinfection  of  clothing  or  the  washing  of 
walls,  floors,  furniture,  etc. 

A  2  or  3  per  cent,  solution  of  a  mixture  of  equal  ]iarts 
of  carbolic  and  sulphuric  acids  is  valuable  for  the  disin- 
fection of  water-closets,  urinals,  etc.,  as  the  latter  acid 
increases  the  effectiveness  of  the  mixture  ;  but  it  must  not 
be  kept  too  long  in  contact  with  metals  on  account  of  the 
corrosive  action  of  the  sulphuric  acid. 

Solutions  of  the  krrsofs  (meta-,  para-,  and  ortho-),  which 
arc  derived  from  coal-  or  wood-tar,  and  much  resemble 


CHEMICAL  DISINFECTANTS.  341 

carbolic  acid,  may  be  used  for  the  same  purposes  and  in 
about  the  same  strength  as  solutions  of  the  latter.  In  fact, 
trikresol,  which  is  a  refined  combination  of  the  three,  is  two 
or  three  times  as  powerful  a  disinfectant  as  carbolic  acid, 
and,  in  solutions  of  from  0.5  to  1  per  cent,  strength,  makes 
an  agreeable  and  efficient  disinfectant  for  use  in  surgery 
and  obstetrics,  especially  as  it  does  not  coagulate  albumin 
as  readily  as  do  carbolic  acid  and  corrosive  sublimate.  As 
carbolic  acid  and  kresol  solutions  are  all  poisonous,  they 
should  always  be  so  labelled,  although  the  characteristic 
odor  serves  as  a  partial  safeguard  to  those  accustomed 
to  it. 

The  kresols  do  not  corrode  metals  and  can  be  used  with 
soaps  and  oils,  both  of  which  features  increase  their  use- 
fulness for  surgical  and  other  purposes. 

Creolin  is  another  coal-tar  product  that  has  some  ger- 
micidal power,  but  is  not  so  efficient  as  was  formerly 
credited.  Being  cheap,  it  may  be  used  freely  for  disinfect- 
ing drains,  stables,  urinals,  and  such  places  where  its 
rather  strong  odor  is  not  objectionable.  It  should  be 
made  up  in  from  2  to  5  per  cent,  strength  in  water,  and, 
being  insoluble,  the  mixture  must  be  thoroughly  stirred  or 
shaken  each  time  before  use. 

ZhiG  chloride  is  a  good  antiseptic  and  deodorant,  but 
not  a  very  powerful  disinfectant.  A  5  or  10  per  cent, 
solution  will  kill  germs  without  spores. 

Calcium  hydrate,  when  mixed  with  water  to  make  a 
thin  whitewash  (milk  of  lime),  is  said  to  be  a  good  disin- 
fectant, especially  for  excreta,  etc.,  and  is  one  of  the 
cheapest  and  easiest  to  obtain.  It  should  be  added  to  the 
infectious  matter  in  excess  or  until  the  mixture  is  de- 
cidedly alkaline,  and  will  require  from  one  to  two  hours 
to  disinfect  thoroughly. 


342  DISINFECTION. 

The  proportion  of  lime  to  water  should  be  about  as  1  to 
4,  equal  parts  being  first  taken  to  allow  the  slaking  of  the 
lime,  and  the  rest  of  the  water  then  added  and  the  mass 
thoroughly  mixed  by  stirring.  Two  quarts  of  this  mixt- 
ure per  day  for  each  person  using  a  cesspool  will  keep  the 
contents  of  the  latter  disinfected  and  free  from  putre- 
factive odors,  provided  its  use  commences  with  the  use  of 
the  cesspool,  or  that  the  prior  contents  have  been  dis- 
infected by  an  excess  of  this  or  a  chlorinated  lime  solu- 
tion, or  by  an  abundance  of  the  latter  salt  or  quicklime  in 
powder. 

Sulphate  of  iron,  which  acts  as  an  antiseptic  to  prevent 
putrefaction,  rather  than  as  a  disinfectant,  may  also  be 
added  to  the  contents  of  an  offensive  cesspool  or  one  that 
has  received  infected  matter  to  the  extent  of  about  four 
pounds  for  each  cubic  yard  of  the  mass.  The  sulphate 
should,  of  course,  be  thoroughly  dissolved  before  using. 

An  extremely  valuable  disinfectant  for  local  or  topical 
applications  to  the  person  is  hydrogen  peroxide  or  dioxide 
(H2O2).  It  is  harmless,  even  when  taken  internally ;  is 
effective  in  comparatively  weak  solutions,  and  is  especially 
active  in  the  destruction  of  pus  organisms.  It  is  usually 
supplied  in  the  form  of  a  15  per  cent,  solution  in  water 
and  at  present  only  its  high  cost  prevents  its  more  ex- 
tended use. 

Until  the  discovery,  in  1892,  of  the  great  disinfecting 
power  of  formaldehyde  or  formic  aldeliyde  by  Trillat  and 
Aronson,  about  the  only  gaseous  disinfectants  of  practical 
value  were  chlorine  and  sulphur  dioxide. 

Of  these,  chlorine  is  the  most  poAverful  and  efficient, 
but  the  distressing  and  oftentimes  serious  symptoms  which 
it  produces  when  accidentally  inhaled,  and  the  bleaching 
effect  that  it  has  upon  many  articles,  have  both  tended  to 


GASEOUS  DISINFECTANTS  343 

prevent  its  common  employment.  Like  the  sulphur 
dioxide,  it  acts  best  in  the  presence  of  moisture,  and 
therefore  steam  should  be  simultaneously  introduced  and 
liberated  in  the  room  or  enclosure  in  which  either  of  these 
disinfectants  is  used.  Sufficient  chlorine  for  1000  cubic 
feet  of  space  may  be  generated  by  carefully  pouring  two 
fluidounces  of  strong  sulphuric  acid  and  three  fluidounces 
of  water,  previously  mixed  and  cooled,  upon  eight  ounces 
of  sodium  chloride  (common  salt)  and  two  ounces  of  man- 
ganese dioxide.  The  acid  must  be  added  to  the  water 
little  by  little  and  with  care,  and  the  salt  and  manganese 
should  be  in  an  earthen  vessel  upon  a  bed  of  sand,  to 
prevent  injury  to  the  floor  or  carpet.  Moreover,  as  the 
chlorine  gas  is  very  heavy,  the  generating  apparatus 
should  be  at  as  high  a  level  as  possible  in  the  room  to  get 
even  fair  diffusion. 

Sulphur  dioxide  (SOj),  though  not  so  positive  in  its 
action  as  chlorine,  is  more  frequently  employed  on  account 
of  the  lesser  risk  and  trouble  connected  with  it.  It  prob- 
al)ly  kills  germs  not  containing  spores  if  sufficiently  con- 
centrated and  in  the  presence  of  moisture,  and  is  therefore 
useful  in  the  fumigation  of  rooms  and  of  articles  that  can- 
not be  subjected  to  steam  heat  or  chemical  solutions.  But 
it  will  bleach  or  tarnish  many  articles,  and  for  this  reason 
and  tlie  fact  that  it  is  thought  by  some  to  be  inferior  to  for- 
maldehyde, it  will  hereafter  probably  be  almost  entirely 
supplanted  by  the  latter  whenever  that  can  be  obtained. 

To  secure  sufficient  concentration  at  least  three  pounds 
of  sulphur  should  be  burned  for  every  1000  cubic  feet 
of  air-space. 

The  sulphur  should  be  well  moistened  with  alcohol, 
unless  the  prepared  sulphur  candles  now  on  the  market 
are  used,  and  allowance  should  be  made  for  a  considerable 


344  DISINFECTION. 

proportion  that  is  usually  not  burned.  Care  must  also  be 
had  to  guard  against  setting  fire  to  the  room  from  the 
sputtering  of  the  sulphur,  and  especially  to  have  present 
in  the  atmosphere  an  abundance  of  aqueous  vapor. 

Before  the  fumigation  of  a  room  with  chlorine  or  sul- 
phur dioxide,  or  with  formaldehyde,  all  ajjertures  and 
crevices  in  the  walls,  ceiling,  or  floor  should  be  carefully 
closed  from  the  outside,  to  maintain  the  gases  in  as  con- 
centrated a  state  as  possible  during  the  process,  which 
should  continue  for  at  least  twenty-four  hours  in  the  case 
of  chlorine  or  sulphur  gas,  and  for  not  less  than  twelve 
hours  with  formaldehyde.  After  the  fumigation  the  room 
should  be  thrown  open  and  well  ventilated,  and  then 
thoroughly  cleansed  with  a  corrosive  sublimate,  carbolic 
acid,  or  hot  soda  solution,  a  4  per  cent,  solution  of  the 
latter  being  not  only  cleansing,  but  strongly  disinfectant 
as  well. 

Sulphur  gas  excels  formaldehyde  in  the  destruction  of 
such  vermin  as  roaches,  bedbugs,  fleas,  flies,  and  mos- 
quitoes, and  may  be  preferred  to  the  latter  or  used  as  an 
adjunct  to  it  where  there  is  danger  of  infection  being 
transmitted  by  these  agents.  Likewise,  it  may  be  used  to 
destroy  larger  animals,  such  as  rats  and  mice,  that  we  now 
know  may  be  carriers  of  various  disease  germs.  (See  pp. 
357  and  372.) 

Hydrocyanic  acid,  wliicli  may  be  freely  liberated  as  a 
gas  by  the  addition  of  dihite  sulphuric  acid  to  cyanide  of 
j)otassiuni,  has  been  used  both  as  a  germicide  and  an  in- 
secticide. Its  high  relative  cost  does  not  warrant  its  use 
as  a  substitute  for  sulphur  gas  or  formaldcliyde,  but  the 
certainty  with  wliieli  it  kills  all  kinds  of  small  vermin, 
and  even  higher  animals,  siicli  as  rats  nnil  mico,  that  may 
carry   infective   organisms,   renders  it   of  high  value   for 


FORMALDEHYDE  AS  A  DISINFECTAyT.         345 

this  purpose.  Its  poisonous  nature,  however,  shouhl 
always  be  remembered,  and  great  care  always  observed  in 
its  use. 

Formaldehyde  (formic  aldehyde),  both  in  its  gaseous 
state  and  in  solution,  is  undoubtedly  one  of  the  best  and 
most  efficient  disinfectants  now  in  use.  It  has  consider- 
able penetrating  power,  although  less  than  steam  or  than 
was  claimed  for  it  at  first  by  its  more  entiuisiastic  advo- 
cates, while  for  surface  disinfection  it  acts  almost  imme- 
diately. It  is,  therefore,  much  better  in  this  respect 
than  chlorine  or  sulphur  dioxide,  already  mentioned,  and 
where  it  is  properly  used,  only  such  articles  as  bedding, 
mattresses  and  pillows,  that  can  be  better  treated  with 
steam,  need  be  removed  from  an  infected  apartment. 
Clothing,  rugs,  hangings,  etc.,  that  can  be  freely  exposed 
to  it  are  quickly  sterilized.  Another  important  feature  is 
that  it  does  not  bleach  nor  act  destructively  on  either  cloth- 
ing or  furniture,  and  that,  although  it  is  quite  irritating  to 
tlie  conjunctiva  of  the  eyes  and  to  other  mucous  mem- 
branes when  concentrated,  it  is  virtually  non-poisonous. 

Formaldehyde  is  readily  absorbed  and  held  in  solution 
by  water  to  the  extent  of  40  per  cent,  by  weight  of  the 
latter,  but  as  soon  as  this  proportion  is  exceeded  there  is 
a  polymerization  of  the  gas  and  a  solid  (paraformalde- 
hyde or  paraform)  is  precipitated,  which  is  only  resolved 
again  into  formaldehyde  at  a  temperature  of  275°  F. 
The  40  per  cent,  solution  is  practically  identical  with  the 
preparation  which  is  commercially  known  as  formalin, 
which  has  usually  an  addition  of  10  per  cent,  of  methyl 
alcohol  to  guard  further  against  precipitation.  Very 
weak  solutions  (1  or  2  per  cent.)  of  the  gas  are  still  effec- 
tively disinfectant,  while  its  virtue  as  an  antiseptic  persists 
even  when  the  dilution  is  carried  to  a  remarkable  decree. 


346 


DISINFECTION. 


One  peculiar  effect  of  the  solutions  is  that  of  rendering 
connective  tissue  and  all  gelatinous  substances  insoluble 
in  eitlier  hot  or  cold  water,  and  it  is  probably  to  this  that 
its  germicidal  activity  is  largely  due,  since  the  food-supply 
of  the  bacteria,  if  not  the  substance  of  the  latter  them- 
selves, is  partly  of  this  nature.  For  the  same  reason  it 
hardens  and  disagreeably  roughens  the  skin,  which  tend 
to  prevent  its  use  for  topical  applications  to  the  human 
body. 

Several  methods  have  been  devised  for  the  production 
or  liberation  of  formaldehyde  in  rooms  and  buildings 
in  such  volume  as  positively  to  secure  both  surface  and 


Fig.  59. 


Fig.  60. 


Schering's  lamps  for  volatilizing  parafcirm. 

penetrative  disinfection.  One  of  the  first  devised  and 
best  methods  involves  the  heating  and  vaporizing  of  a 
solution  of  the  gas,  such  as  formalin  or  formochloral,  the 
latter  a  mixture  of  the  former  with  calcium  chloride. 
For  instance,  in  Trillat's  ap})aratus  the  latter  solution  is 
used,  the  calcium  chloride  being  added  to  insure  further 
against  the  precipitation  of  j)arali)rni.  A  simpler  device, 
called  a  regenerator,  allows  the  I'ormalin  to  flow  in  a  fine 


FORMALDEHYDE  GAS   GENERATORS.  347 

stream  through  a  copper  coil  heated  to  redness  by  a  flame 
beneath,  the  gas  and  vapor  then  passing  directly  into  the 
room  in  a  snperheated  and  effective  condition  ;  and  in  other 
apparatus,  like  the  Novy-Waite  and  Trenner-Lee  genera- 
tors, there  is  special  provision  for  the  rapid  evolution  of 
the  gas  at  high  temperature,  and  to  prevent  its  poly- 
merization. Both  of  these  methods  have  the  advantage 
that  the  apparatus  may  be  operated  outside  of  the  room 
to  be  disinfected,  and  the  action  accordingly  controlled ; 
also  that  the  amount  of  gas  liberated  depends  directly 
upon  the  strength  and  quantity  of  the  solution  evaporated. 

In  the  Schering  method  the  solid  paraform  is  heated 
in  a  receptacle  over  an  alcohol  lamp,  the  volume  of 
resulting  formaldehyde  depending,  of  course,  upon  the 
amount  of  paraform  used.  This  method  has  yielded  some 
excellent  results  experimentally,  and  is  of  special  value 
in  disinfecting  small  rooms,  closets,  and  sterilizing  cases 
for  instruments,  dressings,  etc. 

The  gas  may  also  be  liberated  in  a  room  by  spraying 
formalin  from  a  properly  constructed  compressed  air  or 
steam  atomizer,  or  by  evaporating  it  from  saturated  sheets 
hung  about  the  room,  but  as  this  is  not  certain  to  liberate  all 
the  gas  from  the  solution,  more  of  the  latter  must  be  used. 

Formerly  a  very  common  form  of  apparatus  was  that 
devised,  in  the  form  of  a  portable  lamp,  to  develop  the 
gas  directly  by  the  oxidation  of  methyl  alcohol,  the 
vapors  of  the  latter  being  made  to  pass  over  or  through 
tubes  or  coils  of  heated  platinum,  and  to  be  thus  converted 
into  the  disinfectant  gas.  Considerable  formaldehyde  can 
doubtless  be  produced  in  this  way,  but  with  most  apparatus 
of  this  kind  the  amount  at  any  time  is  uncertain  and  the 
results  indefinite,  since  part  of  the  alcohol  vapors  are 
polymerized  and  part  are  further  oxidized  into  compounds 


348 


DISINFECTION. 


such  as  carbon  monoxide  and  carbon  dioxide.  Therefore, 
with  such  apparatus,  this  method  is  only  to  be  advised 
for  comparatively  small  apartments  or  enclosures,  and  not 
where  certainty  of  disinfection  is  important. 

However,  these  objections  have  been  overcome  in  the 


Fig 


Modified  Novy-Waite  formaldehyde  generator. 


Kuhn  generator,  which  is  simple  and  positive  in  opera- 
tion  aTid  manipulation,  and  has  boon  proved  efficient  and 
reliable  under  severe  tests.  In  this  generator  the  vapor  of 
alcohol  passes  between  two  cones  of  heated  platinized  as- 
bestos, one  of  which  is  so  arranged  as  to  act  as  a  deflector, 
thus    preventing    extreme    and    concentrated    heat    being 


FORMALDEHYDE  GAS  GENERATORS. 


349 


thrown  directly  on  the  surface  of  the  vessel  containing  the 
wood  alcohol.  Any  alcoholic  vapor  which  escapes  the 
action  of  these  platinized  cones  is  then  subjected  to  suc- 
cessive passage  through  five  disks  or  layers  of  platinized 
wire^  commercially  known  as  l^o.  20  mesh^  or  containing 

Fig.  62. 


The  Trenner-Lee  formaldehyde  generator. 


400  openings  to  the  square  inch.  In  this  way  the  alcohol 
is  brought  into  thorough  contact  with  a  platinized  surface, 
and  the  result  is  a  much  more  complete  conversion  into 
formaldehyde. 

Abbott  states  that  he  has  "  obtained  the  most  satisfactory 


350 


DISINFECTION. 


results  through  the  use  of  formalin  to  which  10  per 
cent,  of  glycerin  has  been  added,  as  recommended  by 
Schlossmann ;  and  through  the  employment  of  a  generator 
after  the  plan  of  that  advised  by  JSTovy  and  Waite.  In 
these  tests  we  found  that  80  per  cent,  of  all  exposed  in- 
fected objects  in  a  room  could  be  disinfected  when  500  c.c. 

Fig.  63. 


The  Kuhu  formaldehyde  generator. 

of  the  formalin  glycerin  mixture  per  1000  cubic  feet  of 
air-s})ace  was  completely  evaporated  and  the  room  kept 
closed  for  three  or  four  hours."  ^ 

In   the   other   ajiparatus   one    pound   of   formalin   or 
formochloral,  from  50  to  75  of  Schering's  paraform  tablets, 
1  Hygiene  of  Transmissible  Diseases,  1899,  p.  269. 


AMOUNT  OF  FORMALDEHYDE  NECESSARY.      351 

or  a  quart  of  methyl  alcohol  are  to  be  respectively  used  for 
each  1000  cubic  feet  of  air-space  to  be  disinfected.^ 

A  very  simple  method  of  liberating  formaldehyde  gas 
and  one  whose  efficacy,  it  is  asserted,  has  been  thoroughly . 
established  by  laboratory  tests,  is  to  pour  one  pound  of 
formalin  containing  40  per  cent,  of  formaldehyde  on  six 
ounces  of  permanganate  of  potash  in  a  large  vessel,  this 
being  the  proper  amount  for  1000  cubic  feet  of  space  or. 
less.  The  gas  is  liberated  freely  and  speedily,  and  with 
but  little  risk  of  polymerization  or  of  any  remaining  in 
solution.  Of  course,  the  eifectiveness  of  action  will  be 
enhanced  by  the  previous  or  coincident  vaporizing  of 
water  in  the  room. 

Whenever  formaldehyde  is  employed  as  a  gas,  all  the 
apertures  in  the  room  should  be  carefully  and  tightly 
closed,  since,  having  the  same  specific  gravity  as  the  air, 
its  diffusion  takes  place  rapidly.  Moreover,  after  a  suffi- 
cient volume  of  the  gas  has  been  liberated,  it  should  be 
allowed  to  act  as  long  as  possible,  preferably  for  twelve 
hours  at  least,  and  better  for  twenty-four,  since,  though  it 
is  more  rapid,  the  time  element  is  just  as  important  a 
factor  with  this  as  with  other  disinfectants.  Fliigge  thinks 
we  obtain  good  results  if  90  per  cent,  of  the  disease  gerrns 
present  are  killed  by  the  formaldehyde  fumigation. 

Lastly,  the  gas  is  an  excellent  deodorant,  combining  as 
it  does  with  the  effluvia  from  decomposing  substances  to 
produce  odorless  compounds.  Its  odor,  in  turn,  may  be 
quickly  dissipated  from  a  room  by  evaporating  a  little 
ammonia  therein. 

The  following  table  of  Koch  and  Jaeger  is  added  to 
show  the  comparative  disinfectant  strength  of  some  sub- 
stances occasionally  used  for  the  purpose  : 

^  See  also  U.  S.  Quarantine  Eegulations,  as  quoted  on  p.  355. 


352 


DISIXFECTION. 


JHsivfectarU 


Strength. 


Objects  submitted 
to  experiments. 


_.  ,1     .-,      X-  (   1  to  20,000       Anthrax  spores 

Bichloride  of  mercury  -^  „        .      ,  *^ 

I    1  to    1,000        Anthrax  spores 


Silver  nitrate 


1  to  12,000 
i,000 
1,500 


f  1  to  12,0 
-^  Ito  4,0 
(-  1  to    2,u 


Acid,  hydrochloric 

Acid,  sulphuric  .   . 

Ferrum  chlorate  . 
Calcium  chloride  . 
Potass,  permanganate 

Caustic  lime  . 
Acid,  carbolic  . 


2  to 

100 

/  2to 

100 

■  ■  1 15  to 

100 

5  to 

100 

5  to 

100 

:e    5  to 

100 

J  0.0246  to 

100 

1 0.0074  to 

100 

'■10  to 


Formaldehyde 
(K.  Walter.) 


[ 


3  to 


100 
100 
100 


Anthrax  spores 
Cholera  and  typhoid 
Diphtheria 
Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Cholera 
Typhoid 
Staphylococcus  and  ) 

streptococcus  pyog.  / 
Anthrax  spores 
/yearly   all   patho-"|    Less  than 

*-     genie  germs         J    30  minutes. 

Anthrax  spores  15  minutes. 

All  other  pathogenic  |     ^  j^^jj^^^g 

germs 


T^me  required 

for  destruction, 

10  minutes. 

1  minute. 
70  hours. 

2  hours. 
2  hours. 

10  days. 
53  days. 

8  days. 

6  days. 

5  days. 
1  day. 

6  hours. 
6  hours. 


8-11  seconds. 
24  hours. 


In  any  case  of  infectious  disease  special  attention  should 
be  given  to  disinfecting  the  excretions  and  secretions 
which  are  known  to  be  most  likely  to  contain  the  disease 
germs,  viz.,  the  desquamating  epithelium  and  likewise  the 
renal  secretion  in  measles,  scarlet  fever,  and  all  the  exan- 
themata ;  the  dejecta  and  urine  in  typhoid  fever,  cholera, 
tropical  or  infectious  dysentery,  and  in  tuberculosis  of 
the  intestinal  or  genito-urinary  tract ;  the  sputum  in 
tuberculo.sis  of  the  lungs  and  air-passages,  and  in  in- 
tiuciiza,  pneumonia,  and  diphtheria;  secretions  from  the 
throat  and  nose  in  diphtheria,  scarlet  fever  and  measles; 
discharges  from  abscesses,  suppurating  or  gangrenous 
wounds,  etc. 

During  the  course  of  the  illness  there  should  be  no 
more  communication  than  is  absolutely  neces.sary  between 
the  occupants  of  the  sick-room  and  those  in  the  rest  of 
the  hou.se,  and  a  sheet  should   be  hung  at  the  door  and 


SICK-ROOM  PRECAUTIONS.  353 

kept  moist  with  some  disinfecting  solution,  as  this  will 
largely  prevent  the  escape  of  infected  dust  particles 
through  the  doorway.  All  articles  going  from  the  room, 
wliether  dishes,  clothing,  or  food,  should  be  submerged  iu 
a  disinfectant  or  covered  with  a  cloth  wet  with  it,  and 
should  be  burned,  boiled,  or  otherwise  disinfected  as  soon 
as  possible  thereafter.  Excreta  should  be  disinfected  as 
soon  as  discharged  from  the  body,  but  should  not  be 
emptied  into  a  water-closet,  sewer,  or  cesspool  till  the  dis- 
infectant has  had  ample  time  to  do  its  work,  at  least  one 
hour  being  given  for  this  action.  Ventilation  should  be 
as  perfect  as  possible  ;  sunlight  should  be  admitted  when- 
ever it  will  not  injure  or  annoy  the  patient,  and,  above 
all,  cleanliness  in  every  respect  should  be  insisted  upon  as 
being  most  essential. 

The  dress  of  the  nurse  or  attendant  should  be  such 
that  dust  and  germs  do  not  readily  adhere  to  it  and  that 
it  may  readily  be  disinfected  and  cleaned,  the  cotton  uni- 
forms of  a  hospital  training  school  being  almost  ideal  in 
this  respect.  If  this  were  in  the  form  of  an  overgarment 
that  could  readily  be  slipped  oflP  when  the  nurse  has  to 
leave  the  sick-room,  there  would  be  an  additional  element 
of  safety,  just  as  there  will  be  if  there  is  provided 
something  like  a  long,  old-fashioned  linen  "  duster "  for 
the  casual  visitor,  whether  physician  or  parent,  to  slip  on 
when  entering  the  room.  The  nurse  should,  of  course, 
bathe  not  only  the  patient  but  herself  as  well  with  disin- 
fectant solutions,  such  as  Labarraque's  (diluted),  carbolic 
acid,  or  trikresol ;  should  destroy  at  once  all  possible  infec- 
tion coming  from  the  patient,  and  at  least  every  other  day 
should  wipe  with  a  cloth  dampened  in  a  disinfectant  all 
window-sills,  tables,  and  other  liorizontal  surfaces  upon 
which  dust  and  the  attached  germs  continually  settle.     A 

23 


354  DISINFECTION. 

closet  with  a  close-fitting  door  may  be  made  to  serve  as  a 
good  disinfecting  chamber  for  garments  that  are  not  in 
immediate  use,  as  a  few  ounces  of  formalin  sprinkled  on 
the  garments  themselves  or  a  few  paraform  tablets  burned 
in  one  of  the  Schering  lamps  will  quickly  sterilize  the 
contents  of  the  closet  without  serious  discomfort  to  the 
occupants  of  the  adjoining  room. 

It  is  taken  for  granted  that,  if  possible,  before  the  occu- 
])ancy  of  the  room  by  the  sick,  all  upholstered  furniture, 
heavy  drapery,  and  everything  not  absolutely  necessary 
were  removed  from  the  room.  Even  the  carpet  should 
be  taken  up  and  rugs  used  temporarily  in  its  place.  If 
this  is  done,  the  work  of  disinfecting  the  room  after  it 
is  no  longer  needed  by  the  patient  will  be  greatly  facili- 
tated. 

Where  the  use  of  formaldehyde  is  not  available,  the 
final  disinfection  should  be  carried  out  as  follows  :  All 
bed-clothing,  etc.,  should  be  either  submerged  in  some 
disinfectant  solution  or  in  boiling  water,  or  else  covered 
with  a  sheet  wet  with  a  disinfectant,  and  boiled  as  soon 
as  possible  thereafter.  No  clothing  should  be  sent  away 
from  the  house  to  be  laundered.  Bed-quilts,  blankets, 
mattresses,  etc.,  should  be  subjected  to  steam  sterilization 
if  possible;  if  not,  the  blankets  and  quilts  should  be 
carefully  sterilized  by  boiling,  and  the  mattresses  would 
better  be  burned,  though  they  may  be  disinfected  inter- 
nally l)y  the  introduction  of  formalin  or  formaldehyde  gas. 
The  carpet  or  rugs  should  be  carefully  taken  uj),  carried 
to  an  open  space,  Mcll  beaten,  and  then  hung  in  the  open 
air  for  a  time,  ])rovided  they  cannot  be  sent  at  once  to 
some  ])la(re  where  steam  sterilization  is  available.  All 
lurniture  and  the  woodwork  of  the  room  should  be 
washed    with    corrosive    sublimate    solution    (1    to    1000 


TREATMENT  OF  INFECTED  ROOMS.  355 

or  500),  taking  care  to  get  the  fluid  into  all  crevices. 
Tlie  floor  may  be  scrubbed  with  lye  or  hot  soda  solution 
(4  per  cent.),  and  then  mopped  and  flooded  with  a  corro- 
sive sublimate  solution.  The  walls  should  also  be  wiped 
with  cloths  wrung  out  of  this  solution,  and  any  paper  upon 
them  removed  before  fumigation,  unless  it  be  new  and 
free  from  cracks.  Or  the  walls  may  be  rubbed  down 
with  crumbs  of  bread  and  the  latter  burned,  as  the  bread 
contains  much  gluten,  to  which  the  dust  and  bacteria 
adhere.  Fumigation  with  chlorine  or  sulphur  dioxide  is 
usually  of  somewhat  doubtful  efficiency  unless  consider- 
able attention  is  given  to  the  details.  If  it  is  employed, 
it  should  be  done  first,  before  the  bedding,  etc.,  is  removed 
and  the  walls,  floors,  woodwork  are  wiped  or  washed,  and 
&\\  openings  from  the  room,  cracks,  crevices,  etc.,  should 
be  closed  on  the  outside,  and  sufficient  gas  (chlorine  or 
sulphurous  acid)  liberated  by  suitable  means.  The  vessels 
containing  the  gas-generating  substances  should  be  placed 
in  larger  vessels  containing  water  to  avoid  the  danger  of 
fire,  and  vapor  of  water  should  be  liberated  in  some  way 
simultaneously  with  the  gas,  say  by  placing  hot  bricks  or 
the  like  in  the  water,  or  else  water  should  be  sprayed 
freely  from  an  atomizer  over  everything  in  the  room,  as 
neither  chlorine  nor  sulphurous  acid  has  much  disinfect- 
ing value  except  in  the  presence  of  moisture,  and  the 
effect  of  formaldehyde  is  much  enhanced  by  it.  The 
room  should  then  remain  closed  for  twenty-four  hours, 
and,  lastly,  should  be  well  ventilated  for  a  day  or  two 
before  being  furnished  and  occupied  again. 

Should  it  be  possible  to  use  formaldehyde,  the  disinfec- 
tion is  much  simplified,  and  is  to  be  carried  out  in  the 
way  already  indicated ;  but  whatever  the  gaseous  disin- 
fectant employed,  it   should    always  be  followed  by  the 


356  DISINFECTION. 

"washing  or  wiping  of  walls,  ceilings,  floor,  and  all  exposed 
surfaces  with  a  disinfectant  solution,  and  by  the  steam 
sterilization  or  boiling  of  all  removable  articles  where- 
ever  possible.  In  fact,  it  should  l)e  remembered  tliat 
no  one  of  these  processes  will  in  any  probability  destroy 
all  the  infection,  but  that  each  must  be  carried  out  with 
conscientious  thoroughness  and  strictest  attention  to  detail 
in  order  to  secure  the  greatest  measure  of  success. 

The  United  States  Quarantine  Regulations,  promul- 
gated April  1,  1903,  authorize  the  following  disinfectants 
and  the  metJiods  of  generating  and  using  them  : 

Physical  Disinfectants. — Burning  :  Of  unquestioned 
efficiency,  but  seldom  required. 

Boiling :  Very  efficient  and  of  wide  range  of  applica- 
bility. The  articles  must  be  wholly  immersed  for  not  less 
than  thirty  minutes  in  water  actually  boiling  (100°  C.J. 
The  addition  of  1  per  cent,  of  carbonate  of  soda  renders 
the  process  applicable  to  polished  steel,  cutting  instru- 
ments or  tools. 

Steam:  (a)  Flowing  steam  (not  under  pressure).  Flow- 
ing steam  (not  under  pressure)  when  applied  under  suit- 
able conditions  is  an  efficient  disinfecting  agent.  The 
exposure  must  be  continued  thirty  minutes  after  the  tem- 
perature has  reached  100°  C. 

(h)  Steam  under  pressure  without  vacuum.  Steam 
under  ])ressure  will  sterilize,  provided  that  the  process  is 
continued  twenty  minutes  after  the  pressure  reaches  15 
pounds  per  square  inch.  The  air  must  be  expelled  from 
the  apparatus  at  the  beginning  of  the  process.  If  im- 
])racticabl('  t(<ol)tain  the  designated  pressure,  a  longer  ex- 
posure will  :ir((,iH])lisli  the  same  result. 

((?)  Steam  under  pressure  with  vacuum.  Steam  in  a 
special   apparatus   with    vacuum    attachment   is  the  best 


QUARANTINE  REGULATIONS.  357 

method  of  applying  steam  under  pressure,  the  object  of 
tlie  vacunm  apparatus  being  to  expel  the  air  and  to  pro- 
mote the  penetration  of  the  steam.  The  process  is  to  be 
continued  for  twenty  miuutes  after  the  pressure  reaches 
10  pounds  to  the  square  inch. 

Gaseous  Disinfectants. — Sulphur  dioxide:  Sulphur 
dioxide  is  efficient,  but  requires  the  presence  of  moisture. 
It  is  only  a  surface  disinfectant,  and  is  lacking  in  pen- 
etrating properties.  An  atmosphere  containing  4.5  per 
cent,  can  be  obtained  by  burning  5  pounds  of  sulphur 
per  1000  cubic  feet  of  space.  This  amount  would  require 
the  evaporation  or  volatilization  of  about  one  pint  of  water. 
Under  these  conditions  the  time  of  exposure  should  not 
be  less  than  twenty-four  hours  for  bacterial  infections. 
A  shorter  time  will  suffice  for  fumigation  necessary  to 
kill  mosquitoes  and  other  vermin. 

The  sulphur  may  be  burned  in  shallow  iron  pots  (Dutch 
ovens)  containing  not  more  than  30  pounds  of  sulphur 
for  each  pot,  and  the  pots  should  stand  in  vessels  of 
water.  The  sulphur  pots  should  be  elevated  from  the 
bottom  of  the  compartment  to  be  disinfected  in  order  to 
ol)tain  the  maximum  possible  percentage  of  combustion  of 
sulphur.  The  sulphur  should  be  in  a  state  of  fine  division, 
and  ignition  is  best  accomplished  by  alcohol ;  special  care 
to  be  taken  with  tliis  method  to  prevent  damage  to  cargo 
of  vessel  by  fire ;  or  the  sulphur  may  be  burned  in  a  special 
furnace,  the  sulphur  dioxide  being  distributed  by  a  power 
fan.     This  method  is  peculiarly  applicable  to  cargo  vessels. 

Liquefied  sulphur  dioxide  may  be  used  for  disinfection 
in  place  of  sulphur  dioxide  generated  as  above,  it  being 
borne  in  mind  that  this  process  will  require  two  pounds 
of  the  licpiefied  gas  for  each  pound  of  sulphur  as  indicated 
iu  the  above  paragraphs. 


358  DISINFECTION. 

Sulphur  dioxide  is  especially  applicable  to  the  holds  of 
vessels,  or  to  freight  cars  and  apartments  that  may  be 
tightly  closed  and  Avliich  do  not  contain  objects  injured  by 
the  gas.  Sulphur  dioxide  bleaches  fabrics  or  materials 
dyed  with  vegetable  or  aniline  dyes.  It  destroys  linen 
or  cotton  goods  by  rotting  the  fiber  through  the  agency 
of  the  acids  formed.  It  injures  most  metals.  It  is 
promptly  destructive  to  all  forms  of  animal  life.  This 
property  renders  it  a  valuable  agent  for  the  extermination 
of  rats,  insects,  and  other  vermin. 

Formaldehyde  Gas. — Formaldehyde  gas  is  effective 
if  applied  by  one  of  the  methods  given  below.  Formal- 
dehyde gas  has  the  advantage  as  a  disinfectant  that  it 
does  not  injure  fabrics  or  most  colors.  It  is  not  poisonous 
to  the  higher  forms  of  animal  life.  It  fails  to  kill  vermin 
such  as  rats,  mice,  roaches,  bedbugs,  etc.  The  method  is 
not  applicable  to  tlie  holds  of  large  vessels.  Formal- 
dehyde is  applicable  to  the  disinfection  of  rooms,  cloth- 
ing, and  fabrics,  but  should  not  be  depended  upon  for 
bedding,  upholstered  furniture,  and  the  like,  when  deep 
penetration  is  required.^ 

Many  formaldehyde  solutions  do  not  contain  40  per 
cent,  of  formaldehyde,  and  all  are  apt  to  deteriorate  with 
time.  It  is  therefore  necessary  to  use  a  quantity  in  excess 
of  the  amount  prescribed  in  these  regulations,  unless  the 
solution  has  been  recently  analyzed. 

The  following  methods  of  evolving  the  gas  may  be 
used : 

(a)  Autoclave  under  pressure,  3  to  12  hours'  exposure. 

(b)  Lamp  or  generator,  6  to  18  hours'  exposure. 

(c)  Spraying,  12  to  24  hours'  exposure. 

1  It  should  be  noted  that  formaldehyde  disinfection  is  more  efficient 
in  warm,  moist,  or  still  AA'cathcr  than  in  cold,  dry,  and  windy  weather. 


FORMALDEHYDE  GAS.  359 

((f)  Formaldehyde  and  dry  heat  in  partial  vacuum^  1 
hour's  exposure. 

The  minimum  number  of  hours'  exposure,  as  given 
above,  applies  to  empty  rooms  of  tight  construction 
containing  smooth,  hard  surfaces ;  the  maximum 
number  of  hours  exposure  applying  in  all  cases  to 
textiles  and  other  articles  of  a  similar  kind  requiring 
more  or  less  penetration. 

Autoclave  under  pressure  :  This  method  has  consider- 
able penetrating  power  when  applied  as  detailed  below. 
Rooms  or  apartments  need  no  special  preparation  be- 
yond the  ordinary  closing  of  doors  and  windows.  Pasting, 
caulking,  or  chinking  of  ordinary  cracks  and  crevices  is 
not  necessary.  The  doors  of  lockers  and  closets  and  the 
drawers  of  bureaus  should  be  opened.  In  this  apparatus 
use  formalin  (40  per  cent.),  with  the  addition  of  a  neutral 
salt,  such  as  calcium  chloride  (20  per  cent.).  The  gas 
must  be  evolved  under  a  pressure  not  less  than  45  pounds. 
After  the  gas  is  separated  from  its  watery  solution  the 
pressure  may  be  allowed  to  fall  and  steam  projected  into 
tlie  compartment  to  supply  the  necessary  moisture.  Use 
not  less  than  10  ounces  of  formalin  per  1000  cubic  feet, 
and  keep  the  room  closed  for  three  to  twelve  hours  after 
the  completion  of  the  process.  For  large  rooms  the  gas 
must  be  introduced  at  several  points  as  far  apart  as  pos- 
sible. It  is  applicable  to  the  disinfection  of  clothing  and 
fabrics  suspended  loosely  in  such  a  manner  that  every 
article  is  freely  accessible  to  the  gas  from  all  directions. 

Lamp  or  generator  :  This  method  requires  an  apparatus 
producing  formaldehyde  by  a  partial  oxidation  of  wood 
alcohol,  and  in  using  it  the  room  or  apartment  should  be 
rendered  tight  as  practicable.  Oxidize  24  ounces  of  wood 
alcohol  per  1000  cubic   feet,   and  keep   the   room  closed 


360  DISINFECTION. 

from  six  to  eighteen  hours,  in  accordance  with  the  pro- 
visions in  a  previous  paragraph.  This  method  leaves 
little  or  no  odor.  When  applied  to  clothing  and  textiles, 
the  articles  should  be  suspended  in  a  tight  room  and  so 
disposed  as  to  permit  free  access  of  the  gas.  (See  also 
previous  paragraph.)  The  wood  alcohol  should  be  of  95 
per  cent,  strength,  and  should  not  contain  more  than  5 
per  cent  of  acetone. 

Spraying :  The  formalin  (40  per  cent.)  should  be 
sprayed  on  sheets  suspended  in  the  room  in  such  a  man- 
ner that  the  solution  remains  in  small  drops  on  the  sheet. 

Spray  not  less  than  10  ounces  of  formalin  (40  per  cent.) 
for  each  1000  cubic  feet.  Used  in  this  way  a  sheet  will 
hold  about  5  ounces  without  dripping  or  the  drops  run- 
ning together.  The  room  must  be  very  tightly  sealed 
in  disinfecting  with  this  process,  and  kept  closed  not  less 
than  twelve  hours.  The  method  is  limited  to  rooms  or 
apartments  not  exceeding  2000  cubic  feet.  The  formalin 
may  also  be  sprayed  upon  the  walls,  floors,  and  objects  in 
the  rooms. 

Formaldehyde  with  dry  heat  in  partial  vacuum  :  This 
method  has  superior  penetrating  powers  and  is  specially 
applicable  to  clothing  and  baggage.  The  requirements  of 
this  method  are  (1)  dry  heat  of  60°  C  sustained  for  one 
hour;  (2)  a  vacuum  of  15  inches;  (3)  formaldehyde 
evolved  from  a  mixture  of  formalin  with  a  neutral  salt, 
in  an  autoclave  under  pressure,  using  not  loss  tlian  30 
ounces  of  formalin  (40  percent.)  for  1000  cubic  feet ;  and 
(4)  a  total  exposure,  under  these  combined  conditions,  of 
one  hour. 

The  stated  times  of  exposure  to  sulphur  dioxide  and 
foniialdeliyde  are  sufficient  to  destroy  bacterial  infection 
due  to  non-spore-bearing  organisms,  providing  that  the 


CHEMICAL  SOLUTIONS.  361 

infection  is  present  on  the  surface.  If  the  room  is  of 
peculiar  construction,  so  as  to  impede  the  diffusion  of 
the  gas,  or  if  the  room  is  a  dirty  one,  or  if  on  account  of 
any  other  condition  rendering  the  germicidal  action  of 
the  gas  more  difficult,  the  time  of  exposure  should  be 
proportionately  increased,  or  supplanted  by  other  methods. 

Chemical  Solutions. — Bichloride  of  mercury.  Bi- 
chloride of  mercury  is  a  disinfectant  of  undoubted  potency 
and  Avide  range  of  applicability.  It  cannot  be  depended 
upon  to  penetrate  substances  in  the  presence  of  albumin- 
ous matter.  It  should  be  used  in  solutions  of  1  to  1000. 
The  solubility  of  bichloride  of  mercury  may  be  increased 
l)y  using  sea  water  for  the  solution,  or  by  adding  2  parts 
per  1000  of  sodium  or  ammonium  chloride  to  the  water 
employed. 

Carbolic  acid  :  Carbolic  acid  in  the  strength  of  5  per 
cent,  may  be  substituted  for  the  ]:)ichloride  of  mercury, 
and  should  be  employed  in  the  disinfection  of  the  cabins 
and  living  apartments  of  ships  to  obviate  injurious  action 
on  polished  metals,  bright  work,  etc. 

Formalin.  Formalin  containing  40  per  cent,  of  for- 
maldehyde may  be  used  in  a  5  per  cent,  solution  as  a 
substitute  for  bichloride  of  mercury  or  carbolic  acid,  and 
is  useful  for  the  disinfection  of  surfaces,  dejecta,  fabrics, 
and  a  great  variety  of  objects,  owing  to  its  non-injurious 
character. 

In  the  foregoing  chapter  the  author  is  much  indebted  to  A.  C.  Abbott's 
Hygiene  of  Transmissible  Diseases  for  authoritative  and  up-to-date  in- 
formation as  to  the  value  of  the  agents  and  methods  of  infection,  and  the 
reader  is  referred  to  this  work  for  an  abundance  of  detail  -which  the 
limits  of  the  present  volume  do  not  permit. 


CHAPTER    XI. 

QUARANTINE. 

Quarantine  may  be  described  as  the  methods  and 
n»easures  imposed  by  a  government — local,  State,  or  na- 
tional— ^to  prevent  the  introduction  of  infectious  disease 
into  the  country  or  from  one  locality  to  another.  Although 
the  term  in  itself  is  misleading,  being  derived  from  the 
Italian  quarante  (forty),  and  signifying  the  period  of 
detention  of  the  first  Venetian  quarantines,  it  is  now 
generally  taken  to  indicate  the  entire  routine  of  inspec- 
tion, disinfection,  and  detention,  without  regard  to  the 
length  of  time  involved. 

While  all  civilized  nations  have  from  the  earliest  times 
recognized  the  importance  of  separating  those  afflicted 
with  epidemic  disease  from  the  well,  the  development  of 
the  idea  and  practice  of  quarantine  has  necessarily  been 
consequent  upon  the  growth  of  commerce;  and  while 
there  liad  practically  always  been  isolation  for  lci>rosy, 
the  first  quarantine  enactments,  in  our  meaning  of  the 
term,  were  put  in  force  in  Venice  about  the  beginning  of 
the  fifteenth  century  as  a  barrier  to  both  the  black  and 
the  Egyptian  plague.  Then  it  was  realized  that  epidemic 
diseases  were  transmitted  by  those  attacked,  a  bureau  of 
healtli  and  a  hizaretto  were  established,  the  effects  of 
those  who  died  of  the  j)]ague  were  destroyed,  and  the 
period  of  detention  of  incoming  vessels,  passengers,  and 
cixfgoea  was  fixed  at  forfi/  days,  tlie  idea  being  that  this 
pt-riod  was  in  itself  more  or  less  mystic  and  salutary. 

362 


HISTORY  AND  PURPOSE  OF  QUARANTINE.     363 

As  time  went  on  and  the  plague  spread  over  the  whole 
of  Europe,  the  number  of  lazarettos  was  largely  increased, 
especially  in  the  eighteenth  century.  Of  these,  the  one 
at  Marseilles  became  the  most  noted,  not  only  because  it 
was  located  at  one  of  the  most  important  ports  of  the 
Mediterranean,  but  because  of  its  excellent  care  and  man- 
agement. Thanks  to  the  increased  efficacy  of  quarantine 
and  other  sanitary  regulations,  as  the  knowledge  concern- 
ing them  developed,  the  plague  rapidly  subsided  soon 
after  the  beginning  of  the  last  century,  and  interest  in 
it  ^vas  supplanted  by  that  in  relation  to  the  frequent  epi- 
demics of  cholera  and  yellow  fever  that  began  to  alarm 
the  civilized  world  ;  and  it  is  to  prevent  the  ingress  of 
tliese  latter  diseases,  together  with  leprosy,  smallpox,  and 
typhus  fever,  that  the  present  quarantine  regulations  are 
in  the  main  devised. 

With  the  knowledge  already  gained  regarding  the 
nature  and  causes  of  infectious  diseases,  their  periods  of 
incubation,  etc.,  it  is  at  once  evident  that  it  will  be  neither 
necessary  nor  wise  to  fix  upon  a  prolonged  and  arbitrary 
time  during  which  vessels  or  passengers  must  be  detained 
in  quarantine.  All  that  is  needed  is  that  the  proper  in- 
specting officers  shall  be  satisfied  that  there  is  no  danger 
of  infection  entering  the  country,  and,  where  any  deten- 
tion is  necessary,  it  is  only  for  so  long  as  will  suffice  for 
the  disinfection  of  the  vessel,  cargo,  and  passengers'  effects, 
and  to  cover  the  period  of  incubation  of  the  suspected 
disease. 

The  present  quarantine  laws  of  the  United  States,  and 
the  latest  regulations  of  the  Treasury  Department  based 
upon  them,  are  especially  designed  to  afford  the  greatest 
possible  protection  to  the  country  against  the  importation 
of  disease  with  the  least  possible  detention  of  incoming 


364  QUARANTINE. 

vessels  and  passengers.  An  important  innovation  that 
facilitates  both  these  ends  has  been  the  establishment  of 
quarantine  in  foreign  lands,  as  it  were,  viz.,  the  inspec- 
tion and,  if  necessary,  disinfection  by  officers  of  this  gov- 
ernment of  all  vessels,  passengers,  and  cargoes  leaving  a 
foreign  port  for  any  port  of  the  United  States.  This 
undoubtedly  greatly  diminishes  the  danger  of  the  intro- 
duction of  any  contagious  disease;  but  in  addition,  there 
is  that  section  of  the  law  that  j)rovides  that  the  President 
may,  whenever  the  condition  of  afiairs  shall  seem  to  Avar- 
rant  it,  "  prohibit,  in  whole  or  in  part,  the  introduction 
of  persons  and  property  from  such  countries  or  places  as 
he  shall  designate  and  for  such  period  of  time  as  he  shall 
deem  necessary." 

Accordingly,  every  vessel  clearing  from  a  foreign  port 
for  this  country  must  obtain  from  the  United  States  con- 
sular officer  of  the  port,  or  from  the  medical  officer  ap- 
pointed for  the  purpose,  a  bill  of  health,  "  setting  forth 
the  sanitary  history  and  condition  of  said  vessel,  and  that 
it  has  in  all  respects  complied  with  the  rules  and  regula- 
tions in  such  cases  prescribed  for  securing  the  best  sani- 
tary conditions  of  the  said  vessel,  its  cargo,  passengers, 
and  crew."  Before  signing  the  bill  of  health  the  consular 
or  medical  officer  must  be  satisfied  tliat  the  conditions 
certified  to  therein  are  true,  and  must  personally  inspect 
"  all  vessels  from  ports  at  Mdiich  cholera,  yellow  fever,  or 
plague  prevails,  or  at  which  smallpox  or  typhus  fever 
.prevails  in  epidemic  form,"  and  "all  vessels  carrying 
steerage  passengers."  IMoreover  the  vessel  must  be  clean 
in  all  parts  before  taking  on  either  passengers  or  crew, 
and  all  parts  liable  to  infec^tion  must  be  disinfected  if  any 
infectious  disease  has  occurred  on  tin-  last  voyage.  The 
bedding  provided  for  steerage  passengers  must  also  be 


QUABANTIXE  REGULATIONS.  365 

destroyed  or  else  disiufected  before  being  used  on  another 
voyage. 

"  At  ports  "where  cholera  prevails  in  epidemic  form, 
special  care  should  be  taken  to  prevent  the  water  and 
food  supply  from  being  infected.  The  drinking  water 
should  be  boiled  and  the  food  thoroughly  cooked  and  pro- 
tected against  contamination  by  flies,  etc.  Where  yellow 
fever  prevails,  precautions  should  be  taken  to  prevent  the 
introduction  of  mosquitoes  on  board  the  vessel.  At  ports 
or  places  where  plague  prevails,  every  precaution  must  be 
taken  to  prevent  the  vessel  becoming  infected  through 
the  agency  of  rats,  ants,  flies,  fleas,  or  other  animals. 

"  At  all  infected  ports  or  places,  communication  be- 
tween the  vessel  and  shore  should  be  reduced  to  a  min- 
imum." 

The  regulations  also  indicate  what  kind  of  cargo,  com- 
ing from  or  through  infected  districts,  may  or  may  not  be 
shipped,  and  what  kinds  must  invariably  be  disinfected 
under  any  circumstances. 

As  to  the  passengers,  while  they  are  divided  into  two 
classes,  cabin  and  steerage,  no  person  suffering  from 
cholera,  smallpox,  yellow  or  typhoid  fever,  scarlet  fever, 
measles,  or  diphtheria  is  allowed  to  shij) ;  nor  should  pas- 
sengers ship  from  an  infected  port.  Steerage  passengers 
and  crew  wdio  have  been  exposed  to  smallpox  must  be 
vaccinated  before  shipping  unless  they  can  show  proof 
of  immunity  by  former  attack  or  satisfactory  vaccination. 
If  the  steerage  passengers  and  crew  have  been  exposed  to 
typhus  fever  infection,  they  may  not  embark  until  twelve 
days,  and  for  plague,  seven  days,  after  such  exposure  and 
tlio  disinfection  of  their  baggage,  while  steerage  passengers 
from  cholera-infected  districts  must  be  detained  in  suit- 
able quarters  for  five  days,  "  the  said  period  to  begin  only 


366  QUARANTINE. 

after  the  bathing  of  the  passengers,  disinfection  of  all 
their  baggage  and  apparel,  removal  of  all  food  brought 
with  them,  and  isolation  from  others  not  so  treated." 
The  same  rules  as  to  detention  and  disinfection  are  to  be 
applied  to  those  coming  from  places  where  the  plague, 
yellow  fever,  or  smallpox  is  prevalent  in  an  ejjidemic 
form,  and  if  one  of  these  diseases  or  cholera  breaks  out 
in  the  detention  barracks,  there  must  be  a  repetition  of 
the  previous  isolation,  disinfection,  etc.,  dating  from  the 
removal  of  the  last  case.  Cabin  passengers  from  cholera 
or  other  infected  ports  or  districts  should  produce  satis- 
factory evidence  as  to  their  place  of  abode  for  the  five 
days  immediately  preceding  embarkation,  and  if  there  is 
any  reason  for  the  belief  that  any  one  of  these  or  his 
baggage  has  been  infected,  such  passenger  is  to  be  detained 
as  long  as  the  inspecting  officer  may  deem  wise,  and  his 
baggage  is  to  be  disinfected. 

Every  passenger  must  also  have  an  inspection-card, 
stamped  by  the  consular  or  medical  officer,  giving  name 
of  passenger,  and  of  ship  and  port  with  date  of  dej)arture, 
etc. ;  and  all  baggage  of  passengers  must  have  a  label 
bearing  the  seal  or  stamp  of  the  United  States  consular 
or  medical  officer,  the  name  of  port  and  of  the  vessel 
carrying  the  baggage,  and  the  statement  and  date  of 
inspection   or  disinfection. 

It  is  evident  that  if  these  regulations  at  foreign  ports, 
together  with  those  required  at  sea — viz.,  rigorous  clean- 
liness and  free  ventilation  of  the  vessel,  daily  inspection 
by  the  ship's  physician,  isolation  and  disinfection  of  the 
sick,  etc. — be  properly  ol)served,  there  can  be  but  little 
chance  of  the  germs  of  (juai'aiiiiuable  disease  gaining  en- 
trance to  our  country,  and,  since  tlie  duration  of  the  voy- 
age will  in  most  cases  exceed  tl»e  period  of  incubation  of 


ENTRY  OF   VESSELS.  367 

most  of  the  contagious  diseases,  if  none  of  these  manifest 
themselves  on  shipboard  at  sea  there  will  be  no  need  for 
any  detention  at  the  port  of  entry  beyond  that  which  the 
inspecting  officer  stationed  there  requires  for  the  perform- 
ance of  his  duties,  viz.,  to  inspect  the  vessel,  bill  of 
health,  crew  and  passengers,  and  their  lists  and  manifests, 
tlie  ship  physician's  clinical  record  of  all  cases  treated, 
and,  ^vhen  necessary,  the  ship's  log. 

This  inspection  service  is  to  be  maintained  at  every  port 
throughout  the  year,  and  is  in  force  not  only  with  respect 
to  all  vessels  from  foreign  ports,  but  also  regarding  any 
vessel  with  sickness  on  board,  vessels  from  domestic  ports 
where  cholera  or  yellow  fever  prevails,  or  where  small- 
pox or  typhus  fever  prevails  in  epidemic  form,  vessels 
from  foreign  ports  carrying  passengers  having  entered 
a  port  of  the  United  States  without  complete  discharge  of 
passengers  or  cargo,  and  vessels  having  been  treated  at 
national  quarantine  stations  that  are  located  a  consideral)le 
distance  from  the  port  of  entry  of  said  vessels.  More- 
over, the  duties  of  the  inspecting  officer  above  stated  are 
only  the  required  minimum  standard,  and  such  other 
regulations  may  be  added  by  legal  State  or  local  authori- 
ties as  may,  for  special  reasons,  be  necessary. 

If  the  inspecting  or  health  officer  is  satisfied  that  the 
vessel  is  not  infected  and  all  the  foregoing  requirements 
have  been  complied  with,  he  gives  his  certificate,  to  be 
delivered  to  the  collector  of  customs  of  the  port,  and  no 
vessel  is  permitted  to  land  any  of  its  passengers  or  cargo 
unless  it  have  this  certificate,  together  with  the  bill  of 
health,  etc.,  from  the  port  of  departure,  as  evidence  that 
the  regulations  have  been  properly  observed. 

On  the  other  hand,  if  vessels  arrive  under  the  follow- 
ing conditions  they  are  to  be  remanded  by  the  authority 


368  QUARANTINE. 

of  the  Secretary  of  the  Treasury  to  the  nearest  national 
or  other  quarantine  station,  where  proper  accommodations 
and  apphances  are  provided  for  the  necessary  disinfection 
and  treatment  of  the  vessel,  passengers,  and  cargo ;  and 
only  after  treatment  and  after  obtaining  a  certificate  from 
the  proper  officer  that  the  vessel,  cargo,  and  passengers  are 
each  and  all  free  from  infectious  disease  and  from  danger 
of  conveying  the  same,  can  a  vessel  be  admitted  to  entry 
to  the  ports  named  in  the  certificate. 

The  conditions  under  which  arriving  vessels  are  to  be 
placed  in  quarantine  are  these  :  "  (a)  With  quarantin- 
able  disease  on  board  or  having  had  such  disease  on  board 
during  the  voyage,"  the  quarantinable  disease  for  the  pur- 
poses of  these  regulations  being  cholera  (cholerine),  plague, 
yellow  fever,  smallpox,  typhus  fever,  and  leprosy,  (b) 
Any  vessel  which  the  quarantine  officer  considers  infected. 
(c)  If  arriving  at  a  port  south  of  the  southern  boundary 
of  Maryland  in  the  season  of  close  quarantine,  March  15 
to  Nov.  1 ,  directly  or  via  a  northern  port,  from  a  tropical 
American  port,  unless  said  port  is  known  to  be  free  from 
yellow  fever,  (d)  In  the  case  of  vessels  arriving  at  a 
northern  port  without  sickness  on  board  from  ports  where 
yellow  fever  prevails,  the  personnel  shall  be  detained 
under  observation  at  quarantine  to  complete  five  days 
from  the  port  of  departure.  (e)  Towboats  and  other 
vessels  liaving  had  communication  Avith  vessels  subject  to 
quarantine  shall  themselves  be  quarantined  if  they  have 
been  exposed  to  infection." 

The  following  exceptions  may  be  made  to  Kules  c  and 
d  with  regard  to  vessels  quarantined  against  on  account 
of  yellow  fever.  "  («)  Vessels  bound  for  ports  in  the  United 
States  north  of  the  southern  boundary  of  Maryland, 
with  good  sanitary  condition  and  history,  having  had  no 


ENTRY  OF   VESSELS.  369 

sickness  on  board  at  ports  of  departure,  en  route  or  on 
arrival,  provided  they  have  been  five  days  from  last 
infected  or  suspected  port,  need  not  be  subject  to  quaran- 
tine." But  if  said  vessels  carry  passengers  destined  for 
places  south  of  this  latitude,  the  baggage  of  said  pas- 
seno-ers  shall  be  disinfected,  and  such  baggage  shall  be 
labeled,  (h)  Vessels  engaged  in  the  fruit  trade  may  be 
admitted  to  entry  without  detention,  provided  they  have 
complied  in  all  respects  with  the  special  rules  and  regula- 
tions made  by  the  Secretary  of  the  Treasury  with  regard 
to  vessels  engaged  in  said  trade."  ^ 

Moreover,  all  passengers  other  than  those  occupying 
first  or  second  cabin,  and  all  persons  arriving  on  vessels 
that  have  had  smallpox  on  board,  must  be  vaccinated 
or  detained  in  quarantine  not  less  than  fourteen  days, 
unless  they  can  show  satisfactory  evidence  of  recent  vac- 
cination or  of  having  had  smallpox  ;  and  all  effects  and 
compartments  liable  to  convey  infection  must  be  disin- 
fected. 

Vessels  arriving  at  quarantine  with  leprosy  on  board 
shall  not  be  granted  pratique  until  the  leper  with  his  or 
her  baggage  has  been  removed  from  the  vessel  to  the 
quarantine  station.  Xo  alien  leper  shall  be  landed.  If 
the  leper  is  an  alien  passenger  and  the  vessel  from  a  for- 
eign port,  action  will  be  taken  as  provided  by  the 
immigration  laws  and  regulations  of  the  United  States. 
If  the  leper  is  an  alien  and  a  member  of  the  crew,  and  the 
vessel  is  from  a  foreign  port,  said  leper  shall  be  detained 
at  quarantine  at  the  vessel's  expense,  until  taken  aboard 
by  the  same  vessel  when  outward  bound."  "^ 

There  are  ten  national  quarantine  stations  and  a  number 

'  Quarantine  Laws  and  Eegulations  of  the  United  States. 
-  Ibid. 
24 


370  QUARANTINE. 

of  others  under  State  or  municipal  control ;  those  which 
have  steam  disinfection  chambers  and  other  efficient 
equipments  are  located  at  Portland,  Me.;  Boston,  Xew 
York,  Sandy  Hook,  Delaware  Breakwater,  Reedy  Island 
in  the  Delaware  River,  Ca[)e  Charles,  Baltimore ;  AVil- 
minijton,  N.  C;  Savannah,  Blackbeard  Island,  Ga.; 
Charleston,  Dry  Tortugas,  Key  West,  Mullet  Keys,  Pen- 
sacola.  Mobile,  Chandeleur  Islands,  New  Orleans,  Gal- 
veston, San  Diego,  San  Francisco,  and  Port  Townsend  ; 
the  ten  national  ones  being  included  in  the  list. 

The  essential  requisites  for  a  properly  equipped  quaran- 
tine station,  after  the  selection  of  a  proper  location — which 
should  be  convenient,  but  not  in  the  line  of  future  city 
growth — are  the  following:^  1.  A  boarding  station,  in- 
cluding boat-house  and  boatmen's  quarters.  2.  A  board- 
ing-boat, preferably  a  steamer.  3.  An  anchorage  for  the 
detention  of  infected  vessels.  It  should  be  safely  out  of 
the  track  of  commerce,  convenient  but  not  too  close  to  the 
main  quarantine  establishment,  sheltered,  and  with  good 
holding;  uround  for  anchors.  4.  A  fumio-ation  steamer 
with  appliances  for  generating  and  forcing  sulphurous 
acid  (or  formaldeliyde)  gas  into  vessels,  and  with  tanks 
and  pumps  for  disinfecting  solutions.  5.  A  wharf,  in 
water  at  least  twenty  feet  deep,  and  upon  which  are  con- 
structed a  warehouse,  tanks  for  disinfecting  solutions,  and 
a  disinfecting  house  containing  steam  disinfecting  cham- 
bers. 6.  A  lazaretto  or  hospital  for  the  treatment  of 
contagious  diseases.  7.  A  hospital  for  non-contagions 
diseases.  8.  Barracks  or  quarters  for  the  detention  in 
groups  for  those  who  may  have  been  exposed  to  contagion 
or  infection.  9.  Quarters  for  medical  officers.  10.  A 
cremation  furnace. 

1  Eohe's  Ilygieue. 


TREATMENT  OF  INFECTED    VESSELS.  371 

When  a  vessel  is  remanded  to  quarantine  by  the  in- 
specting officers  at  a  port  of  entry,  its  treatment  and  that 
of  its  cargo  and  passengers  will  depend  largely  upon  the 
disease  Avith  which  it  is  infected,  being  more  severe  if  the 
latter  is  cholora  or  yellow  fever.  In  case  of  infection  by 
either  of  these  diseases  the  vessel  is  at  once  sent  to  the 
anchorage,  and  must  remain  there  until  the  passengers 
have  been  discharged  and  the  vessel  purified,  and  in  any 
case  there  must  be  no  direct  communication  allowed  be- 
tween quarantine  or  a  vessel  in  quarantine,  and  any  per- 
son or  place  outside. 

Moreover,  if  cholera  has  occurred  on  board,  all  passen- 
gers and  all  of  the  crew,  except  such  as  are  necessary  to 
care  for  her,  must  be  at  once  removed,  the  sick  to  be  sent 
to  the  lazaretto  or  hospital,  others  specially  suspected 
must  be  carefully  isolated,  and  the  remainder  separated 
into  small  groups,  between  which  there  must  be  no  com- 
munication. Those  who  are  especially  liable  to  convey 
infection  must  be  bathed  and  furnished  with  sterile  cloth- 
ing before  entering  the  barracks,  and  no  articles  capable 
of  carrying  infective  matter,  especially  food,  should  be 
taken  into  the  barracks.  If  the  disease  has  occurred  in 
the  steerage,  all  the  steerage  passengers  must  be  bathed 
and  their  clothing  disinfected  ;  and  in  any  case  all  steerage 
baggage  and  eflFects,  and  any  other  baggage,  etc.,  that  has 
been  exposed  to  the  infection,  all  articles  of  the  cargo 
likely  to  be  infected,  and  all  furniture,  living  apartments, 
and  such  other  portions  of  the  vessel  as  may  possibly  re- 
tain or  convey  infection  must  be  disinfected.  The  water- 
supply  must  be  changed  at  once,  the  tanks  thoroughly 
disinfected  by  steam  or  ])otassium  permanganate  solution, 
and  refilled  with  water  from  a  pure  source  or  with  water 
recently  boiled.     The  water-ballast  of  a  cholera-infected 


372  QUARANTINE. 

vessel,  or  of  one  from  a  cholera-infected  port,  should 
never  be  discharged  in  fresh  or  brackish  water  without 
previous  disinfection,  and  the  ballast  tanks  should  be  re- 
filled with  sea- water  or  else  be  disinfected  before  refilling. 
Xothino;  is  to  be  thrown  overboard  from  a  cholera- 
infected  vessel  in  quarantine,  but  everything  that  is  to  be 
destroyed,  even  deck-sweepings,  should  be  burned  in  the 
furnace. 

The  disinfection  of  the  holds  of  vessels  is  to  be  by 
mechanical  cleansing,  by  an  acid  bichloride  of  mercury 
solution  (1  to  800)  applied  under  pressure,  and  by  sul- 
phurous acid  gas  (10  per  cent,  per  volume  strength),  for 
from  twenty-four  to  forty-eight  hours.  All  ballast  must 
be  discharged  or  disinfected  before  the  disinfection  of  the 
hold,  and  all  solid  ballast  must  be  disinfected  before  being 
discharged  into  fresh  water.  The  steerage  and  forecastle 
are  to  be  disinfected  by  live  steam,  if  possible,  for  at  least 
half  an  hour,  and,  if  not,  by  sulphur  dioxide  and  bichlo- 
ride solution,  as  was  the  hold.  Baggage,  bedding,  carpets, 
etc.,  are  to  be  removed  with  caution  and  to  be  disinfected 
by  steam  or  by  boiling,  and,  finally,  all  woodwork  of  the 
vessel  is  to  be  thoroughly  cleansed  mechanically  and 
then  washed  with  an  acid  bichloride  of  mercury  solution 
(1  to  1000). 

The  following  Rules  for  the  application  of  disinfectants 
in  quarantine  work  were  issued  as  part  of  the  quarantine 
regulations  of  the  United  States  Government  on  April  1, 
1903  : 

"  Application  of  Disinfectants  in  Quarantine  Work. 

— The  hi  lids  of  iiv)n  vessels,  empty,  sliall  l)e  disinfected 
by  either  : 

(a)  8u][)hnr  dioxide  generated  by  burning  sulphur  5 
pounds  per  1,000  cubic  feet  of  air  space,  or  liberated  from 


mSIXFECTAXTS  IX  QUARAXTiyE   WORK.       373 

10  pounds  of  liquid  sulphur  dioxide,  sufficient  moisture 
being-  present  in  both  cases;  time  of  exposure,  twenty-four 
hours, 

(b)  AVashing  with  a  solution  of  bichloride  of  mercury, 
1  :  1,000. 

Holds  of  wooden  vessels,  empty,  shall  be  disinfected  by  : 

(a)  Sulphur  dioxide  in  the  manner  prescribed  above, 
followed  by  : 

{b)  AVashing  with  a  solution  of  bichloride  of  mercury. 

In  the  case  of  all  vessels,  both  iron  and  wooden,  ^^•hen 
treated  for  yellow  fever  or  plague  infection,  the  first  pro- 
cess shall  be  a  preliminary  fumigation  by  sulphur  dioxide 
in  the  manner  previously  stated,  in  order  to  insure  the 
destruction  of  mosquitoes,  rats,  and  other  vermin. 

Holds  of  cargo  vessels,  when  cargo  cannot  be  removed, 
shall  be  disinfected  in  so  far  as  possible  by  sulphur  dioxide, 
not  less  than  4  per  cent,  per  volume  strength,  and  where 
possible  this  should  be  generated  from  a  furnace  to  min- 
imize danger  of  fire  in  cargo. 

Living  apartments,  cabins,  and  forecastles  of  vessels 
shall  be  disinfected  by  one  or  more  of  the  following 
methods  : 

(a)  Sulphur  dioxide,  the  destructive  action  of  the  gas 
on  property  being  borne  in  mind. 

(/')  Formaldehyde  gas. 

(e)  Washing  with  solution  of  bichloride  of  mercury, 
1  : 1,000  or  5  per  cent,  solution  of  formalin,  or  5  per 
cent,  solution  of  carbolic  acid,  preference  being  given  to 
carbolic  acid  for  application  to  polished  woods,  bright 
metals,  and  other  objects  injured  by  metallic  salts. 

The  forecastle,  steerage,  and  other  living  apartments  in 
bad  sanitary  condition  must  be  disinfected  by  method  a 
followed  by  method  c. 


374  .  QUARANTINE. 

Mattresses,  pillows,  and  heavy  fabrics  are  to  be  disin- 
fected by  : 

(a)  Boiling. 

(b)  Flowing  steam,  i.  e.,  steam  not  under  pressure. 

(c)  Steam  under  pressure. 

(d)  Steam  in  a  special  apparatus  with  vacuum  attach- 
ment. 

Clothing,  fabrics,  textiles,  curtains,  hangings,  etc.,  may 
be  treated  by  either  of  the  above  methods  from  a  to  d 
inclusive,  as  circumstances  may  demand,  or  by  formal- 
dehyde gas  or  sulphur  dioxide  where  the  article  is  of  a 
character  which  will  not  be  damaged  by  sulphur  dioxide. 

Articles  injured  by  steam,  such  as  leather,  furs,  skins, 
rubber,  trunks,  valises,  hats  and  caps,  bound  books,  silks, 
and  fine  woolens  should  not  be  disinfected  by  steam. 
Such  articles  should  be  disinfected  by  formaldehyde  gas 
or  by  any  of  the  agents  allowed  in  these  regulations  which 
may  be  applicable  thereto.  Those  which  will  be  injured 
by  wetting  should  be  disinfected  by  a  gaseous  agent. 

Clothing,  textiles,  and  baggage,  clean  and  in  good  con- 
dition, but  suspected  of  infection,  can  be  efficiently  and 
least  injuriously  disinfected  by  formaldehyde  gas,  gen- 
erated by  one  of  the  methods  previously  described. 

Textiles  which  are  soiled  with  the  discharges  of  the  sick 
or  presumably  are  deeply  infected,  must  be  disinfected  by  : 

(a)  Boiling. 

(6)  Steam. 

(e)  Immersion  in  one  of  the  germicidal  solutions. 
Cooking  and  eating  utensils  are  always  to  be  disinfected 

by  immersion  in  boiling  water  or  by  steam." 

As  to  the  passengers  and  others  who  have  been  isolated 
in  groups,  they  are  to  be  inspected  twice  daily  by  the 
physician  and   remain    under   his    constant    surveillance, 


DISINFECTION  OF   VESSELS.  375 

and  can  have  no  communication  with  any  one  in  a 
dilfereut  group  or  outside  of  quarantine,  except  through  the 
quarantine  ofRcer.  The  water-supply  and  food-supply  are 
to  be  strictly  guarded,  and  are  issued  to  each  group  sepa- 
rately. The  latter  is  to  be  simple  in  character  and  abun- 
dant in  quantity,  but  no  fruit  is  to  be  permitted.  Strict 
cleanliness  is  to  be  enjoined,  disinfection  wherever  neces- 
sary, and,  in  case  cholera  or  other  disease  appears  in  any 
group,  the  sick  will  be  immediately  removed  to  the  hos- 
pital, and  the  rest  of  the  group  bathed  and  their  eflFects 
disinfected,  and  all  of  them  removed  to  other  quarters,  if 
possible.  None  are  to  leave  quarantine  until  five  days 
after  the  last  exposure  to  infection  and  the  final  disinfec- 
tion of  such  effects  as  were  taken  to  barracks ;  and  no 
convalescent  may  leave  quarantine  until  a  bacteriological 
examination  shows  him  to  be  free  from  infection. 

As  has  been  stated,  the  treatment  of  vessels  infected 
by  other  diseases  is  not  necessarily  so  severe  as  the  above, 
but  in  each  case  every  effort  is  made  to  allow  no  loophole 
for  the  entrance  of  infection  into  the  country ;  and  in  the 
case  of  yellow  fever  there  is  to  be  the  same  isolation  of 
all  not  required  to  care  for  the  vessel  and  a  detention  of 
at  least  five  days  after  disinfection  has  been  thoroughly 
performed  and  completed.  The  detention  for  typhus 
fevei'  is  to  be  twenty  days,  and  for  smallpox  fourteen 
days,  the  detention  dating  from  the  last  exposure  to  either 
disease. 

No  vessel  may  leave  quarantine  until  she  has  a  certifi- 
cate from  the  health  (quarantine)  officer  that  she  has  in 
all  respects  complied  with  the  quarantine  regulations,  and 
that,  in  his  opinion,  she  will  not  convey  quarantinable 
disease.     She  is  then  said  to  be  granted  free  j^ratique. 

The  law  further  provides  that  "  when  practicable,  alien 


376  QUARANTINE. 

ininiigrjints  arriving  at  Canadian  and  Mexican  ports, 
destined  for  the  United  States,  shall  be  inspected  at  the 
port  of  arrival  by  the  United  States  consular  or  medical 
officer,  and  be  subjected  to  the  same  sanitary  restrictions 
as  are  called  for  by  the  rules  and  regulations  governing 
United  States  ports  ;  that  inspection-cards  will  be  issued 
by  the  United  States  officer  at  the  port  of  arrival  to  all 
such  immigrants,  and  labels  affixed  to  their  baggage,  as 
is  required  at  foreign  ports."  Where  such  immigrants 
are  not  inspected  at  the  port  of  arrival  they  shall  enter 
the  United  States  only  at  certain  designated  points  on  the 
frontier,  and  then  only  after  such  inspection,  detention, 
disinfection,  vaccination,  etc.,  as  may  be  necessary  or 
required  by  the  officers  there  stationed. 

There  is  also  provision  for  the  inspection  of  State  or 
local  quarantines  from  time  to  time  by  the  Supervising 
Surgeon-General  of  the  Marine-Hospital  Service,  or  by 
any  officer  of  that  service  detailed  by  him ;  and  for  the 
observance  at  all  quarantines  of  such  additional  rules  and 
regulations  as  may  from  time  to  time  be  promulgated  by 
him. 

Inland  Quarantine. — Under  this  heading  may  be  con- 
sidered the  means  that  may  be  employed  to  prevent  an 
epidemic  extending  from  one  locality  or  district  to  an- 
other, although  the  principle  and  aims  are  practically  the 
same  as  those  of  maritime  quarantines,  viz.,  to  define 
certain  boundaries  beyond  M'hich  no  person  or  thing 
capable  of  carrying  infection  may  pass,  and  to  establish 
certain  points  of  ingress  or  egress  on  these  boundaries 
where  there  may  be  the  necessary  detention,  inspection, 
disinfection,  etc. 

The  sanitary  cm-don  "consists  of  a  line  of  guards,  mili- 
tary or  civil,  thrown  around  a  district  or  locality,  either 


INLAND    QUARANTINE.  377 

to  protect  the  same  from  the  surrounding  country  when 
infected,  or  to  protect  the  surrounding  country  from  the 
infected  district  or  locality."  "  It  is  not  intended  to 
bottle  up  all  the  people  who  are  caught  within  an  infected 
district,  but,  on  the  contrary,  is  intended  as  a  means  of 
exit  to  those  who  will  not  carry  with  them  contagious  dis- 
eases to  the  people  beyond."^  It  may  be  single  or  double; 
in  the  latter  case  the  inner  line  closely  encircles  the  well- 
defined  infected  locality,  and  the  outer  line  the  whole  sus- 
pected territory.  This  latter  may  be  removed  as  soon  as 
it  is  evident  that  the  space  between  it  and  the  inner  line 
is  not  infected.  To  be  efficient  the  cordon  must  be  so 
guarded  that,  even  though  it  be  many  miles  in  length,  no 
unauthorized  person  may  pass  through  it,  while  at  certain 
places  upon  it  camps  of  probation  or  detention  must  be 
established,  where  all  persons  coming  from  the  infected 
locality  may  be  kept  under  observation  for  a  time  equal 
to  the  period  of  incubation  of  the  disease  in  question. 
These  camps  of  probation  or  detention  are  to  be  distin- 
guished from  the  camps  of  refuge,  which  were  first  sug- 
gested by  Surgeon-General  Woodward  in  1878,  and  which 
are  "  simple  residence  camps  established  to  receive  the 
population  of  an  infected  community  when  it  has  been 
determined  to  depopulate  the  infected  district." 

At  these  camps  of  probation  provision  must  be  made 
for  inspecting  every  person  and  disinfecting  all  baggage 
before  entering  camp,  for  isolating  the  occupants  and 
housing  and  feeding  them  in  the  most  comfortable  and 
sanitary  manner  during  the  detention,  for  inspections 
twice  or  thrice  daily,  for  the  isolation  and  care  of  the  sick 
in  hospitals  at  a  safe  distance  from  camp,  and  for  the 
issuance  of  a  certificate  granting  "free  pratique"  when 
the  period  of  detention  is  over. 

*  Eohe's  Hygiene :  "Quarantine." 


378  QUARANTINE. 

A  notable  instance  of  the  sanitary  cordon  was  that  al)Out 
the  city  of  Brownsville,  Texas,  and  along  the  Rio  Grande, 
in  1882;  and  of  a  probation  camp,  that  at  Camp  Perry, 
Florida,  in  1888. 

In  addition  to  these  measures  it  may  be  necessary  or 
advisable  to  establish  a  railroad  quarantine,  as  follows  : 
"  At  certain  convenient  points,  which  will  be  the  only 
points  of  egress  by  rail  from  the  infected  district,  an  in- 
spection service  and  disinfecting  station  are  to  be  main- 
tained throughout  the  epidemic.  Here  all  the  baggage 
and  freight  are  to  be  properly  disinfected  and  all  pas- 
sengers are  to  be  examined  by  the  official  inspectors ;  if 
the  latter  are  from  the  infected  locality,  or  have  not  a 
certificate  from  some  recognized  health  officer  as  to  where 
they  have  been  for  the  previous  days  corresponding  to  the 
incubative  period  of  the  disease,  they  are  to  be  at  once 
remanded  to  the  nearest  camp  of  probation,  there  to 
undergo  the  necessary  detention.  Moreover,  it  may  seem 
advisable  to  prevent  any  passenger  cars  going  beyond  the 
infected  district,  and  to  disinfect  all  freight  and  baggage 
cars  that  do  so." 

There  may  also  be  local  or  house  quarantines  established 
by  nuniicipal  boards  of  health  or  other  authorities  to  pre- 
vent not  only  the  family  or  attendants  of  the  sick  from 
mingling  with  the  rest  of  the  community,  but  also  to 
keep  injudicious  outsiders  from  spreading  the  infection 
througli  unwise  visitations.  And  though  such  isolation 
may  appear  at  times  a  hardsliip  to  certain  individuals, 
and  to  be  unduly  seven*,  one  should  not  forget  the  great 
cost  to  all  concerned  of  epidemics  once  inaugurated,  nor 
that  it  is  by  such  stringent  measures  that  we  shall  be 
able  to  eradicate  the  infectious  maladies  from  our  com- 
munities. 


VACCINATION.  379 

The  foregoing  remarks  apply  likewise  to  other  prophy- 
lactic measures,  such  as,  for  example,  vaccination.  Within 
the  last  five  years  there  have  been  many  epidemics  of 
smallpox  throughout  the  whole  country,  the  extent  and 
spread  of  which  were  due  to  a  very  general  neglect  to 
secure  the  protection  afforded  by  vaccination.  To  contro- 
vert those  who  assert  that  this  prophylactic  measure  is  of 
no  value,  the  following  statistics  are  quoted  from  Mc- 
Farland,  from  Welch  and  Schamberg,  and  from  Harring- 
ton :  Prior  to  the  adoption,  April,  1,  1875,  of  the  German 
law  requiring  vaccination  at  birth  and  at  the  tenth  year,  the 
annual  mortality  in  Prussia,  from  1816  to  1870  was  from 
7.32  to  m  per  100,000  of  population  ;  in  1871  it  was  243.2, 
and  in  1872  it  was  262.67,  owing  to  the  introduction  of 
French  prisoners.  Since  then  there  has  been  no  epidemic, 
but  from  1875  to  1886  the  average  annual  mortality  was 
1.91  per  100,000  and  the  lowest  0.36.  On  the  other  hand, 
from  1870  to  1895  over  20,000  have  died  from  smallpox 
in  Paris  alone,  where  vaccination  is  not  compulsory. 

In  the  following  table,  note  that  vaccination  was  com- 
pulsory in  the  first  five  cities  and  not  enforced  in  the  other 
four ; 

Death-rate  for  Smallpox 

(in  100,000  of  population— 1875-1889). 

Berlin l.]g 

Hamburg 0.74 

Breslau ,    .  1.1 1 

Munich 1.45 

Dresden 1.03 

Paris 26.24 

St.  Petersburg 35.82 

Vienna 64.90 

Prague 147.90 


380  QUARANTINE. 

According  to  Harrington,  in  the  Sheffield  epidemic  of 
1887-'88,  1.55  per  cent,  of  vaccinated  and  9.7  per  cent, 
of  unvacciuated  were  attacked,  the  death-rate  among  the 
former  being  0.7  and  among  the  latter  48  per  1000. 
Among  children  under  ten  the  rate  of  attack  was  5  and 
101  per  1000  respectively  for  vaccinated  and  un vaccinated, 
and  the  death-rate  was  0.09  and  44  per  1000.  From  the 
statistics  of  this  epidemic  we  have  : 

Rates  of  Attack  per  1000  Persons. 

Pei-sons  not  vaccinated      94 

Persons  once  vaccinated 19 

Persons  twice  vaccinated 3 

Death-rates  per  1000  Persons. 

Persons  not  vaccinated     .............    51 

Persons  once  vaccinated 1 

Persons  twice  vaccinated 0.08 

The  same  authority  states  that  a  "  successful  primary 
vaccination  within  three  days  after  exposure  to  existing 
cases  of  smallpox  will  prevent  the  development  of  the 
disease,  and  as  late  as  the  fifth  or  sixth  day  will  either 
prevent  or  modify  an  attack."  So  that  epidemics,  even 
when  well  under  way,  can  be  checked  by  wholesale  vacci- 
nation. 

However,  vaccination  should  be  repeated  from  time  to 
time,  especially  when  there  is  danger  of  infection.  In 
Philadelphia,  in  1901-04,  not  one  of  the  3500  smallpox 
patients  treated  at  the  Municipal  Ho.spital  liad  been  suc- 
cessfully vaccinated,  as  evidenced  by  the  scar,  within  four 
years  of  the  attack,  and  this  in  spite  of  the  fact  that 
about  500,000  persons,  or  one-third  of  the  city's  popula- 
tion, were  vaccinated  during  this  epidemic. 


PROTECTION  AFFORDED   BY   VACCINATION.     381 

From  tlie  data  of  this  hospital,  Welch  and  Schamberg 
compiled  the  following  :  ^ 

Cases.         Deaths.         Percentage 
of  deaths. 
Vaccinated  in  infancy,  good  scars  .    .    .  2335  152  6.5 

"  "       "         fair  scare     .    .    .  1105  135  12.21 

"  "       "         poor  scars  .    .    .  1524  345  22.64 

Postvaccinal  cases 4964  632  12.53 

Unvaccinated 3687        1542  41.82 

Total 8561         2174  25.13 

Again  in  the  same  hospital,  "  during  a  period  of  thirty- 
four  years,  in  which  time  over  9,000  cases  of  smallpox 
have  been  treated,  not  a  physician,  nurse,  or  attendant 
who  had  been  successfully  vaccinated  or  revaccinated  prior 
to  going  on  duty,  contracted  the  disease." 

Surely,  with  modern  statistics  such  as  the  foregoing  at 
hand,  it  is  not  necessary  to  recall  the  excessively  high 
mortalities  of  the  eighteenth  century  prior  to  Jenner's 
discovery,  amounting  to  half  a  million  or  more  annually 
in  Europe,  to  convince  intelligent  persons  of  the  great 
value  of  this  one  method  of  prophylaxis,  and  yet  legal 
compulsion  seems  to  be  necessary  to  secure  its  general 
employment. 

In  the  preceding  pages  the  author  has  attempted  to  present  briefly  the 
principles  and  the  regulations  of  quarantine  as  practiced  in  the  United 
States  at  the  present  time  ;  but  the  reader  is  referred  for  further  details 
to  the  extremely  interesting  and  valuable  chapter  on  the  subject  in 
Eohe's  Text-book  of  Hygiene,  by  Dr.  Wyman,  the  present  Supervising 
Surgeon-General  of  the  Marine-Hospital  and  Public  Health  Service. 

1  Acute  Contagious  Diseases,  page  55. 


CHAPTER  XII. 

THE  EEMOVAL  AXD  DISPOS.IL  OF  SEWAGE. 

The  waste  from  dwellings  is  of  three  kinds  :  house- 
sweepings  and  the  ashes  from  fires ;  the  waste  from 
kitchens,  scraps  of  food,  etc.,  commonly  known  as  garb- 
age ;  and  sewage,  the  most  important,  consisting  as  it 
does  of  the  solid  and  liquid  excreta  of  the  body,  together 
with  waste  water  from  wash-tubs,  bath-tubs,  kitchens, 
laundries,  etc. 

Ashes  alone  have  little  effect  upon  the  health,  except 
that  they  absorb  moisture  readily,  and  if  allowed  to  ac- 
cumulate in  a  cellar  may  do  much  to  keep  it  damp  and 
mouldy.  For  the  same  reason,  if  they  be  mixed  with 
refuse  vegetable  matters,  putrefaction  is  favored  and 
noxious  emanations  given  oif.  The  dust  from  ash  heaps 
may  also  be  carried  into  the  house  and  largelv  increase 
the  solid  impurities  of  the  air  tlierein.  Consequently, 
ashes  should  be  frequently  and  regularly  removed  from 
tlie  premises. 

Kitchen  garbage  readily  decays,  and  if  allowed  to  re- 
main in  the  vicinity  of  the  house  may  pollute  both  the 
air  and  soil  about  it  ;  l)ut  inasmuch  as  it  has  some  value 
as  a  food  for  animals,  there  is  usually  no  difficulty  in 
having  it  removed  In-  scavengers  without  expense  or  delay. 
Care  must  be  had,  however,  that  this  is  done  properly  and 
that  all  rece])tacles  are  ke]>t  in  as  cleanly  a  condition  as 
possible.  ]\Iost  large  cities  now  find  it  safer  to  collect 
382 


SEWAGE.  383 

and  cremate  the  garbage  at  the  expense  of  the  munici- 
pality, rather  than  to  allow  private  individuals  to  keep 
for  its  consumption  large  numbers  of  animals  within  or 
near  the  city  limits.  Even  though  the  former  plan  be  the 
more  costly,  experience  shows  that  this  garbage  may  and 
should  be  consumed  in  properly  arranged  crematories  at 
convenient  localities  without  annoyance  to  the  residents  of 
the  vicinity,  thus  saving  the  expense  and  time  necessary 
for  conveying  the  garbage  beyond  the  municipal  limits. 

The  kind  of  waste  to  which  we  give  the  name  sewage 
is,  however,  of  more  importance  to  sanitarians,  since  it  is 
always  a  possible  factor  in  the  production  of  disease,  and 
since  it  presents  the  most  difficulties  in  respect  to  its 
removal  from  dwellings  and  the  ultimate  disposal  of  it. 

In  addition  to  the  substances  already  named  and  which 
usually  come  from  dwelling-houses,  sewage  may  contain 
the  liquid  excreta  from  stables,  the  refuse  from  factories 
of  all  kinds,  the  drainage  from  polluted  soils,  and  the 
excess  of  rain-water  not  taken  up  by  evaporation  or  re- 
tained in  the  soil.  Its  composition  must  therefore  be 
always  complex  and  variable ;  but  there  will  be  practi- 
cally always  present  in  it  sodium  chloride,  ammonia, 
carbon  monoxide  and  dioxide,  hydrogen  and  ammonium 
sulphide,  fetid  and  decomposing  organic  matter,  and 
myriads  of  bacteria.  Fresh  sewage  will  not  be  so  offen- 
sive to  the  senses  as  that  in  which  putrefaction  has 
commenced,  nor  will  the  gases  arising  from  it  be  so  dan- 
gerous to  health.  Frankland  has  shown  that  "  solid  or 
liquid  matter  is  not  likely  to  be  scattered  into  the  air  from 
the  sewage  itself  by  any  agitation  it  is  likely  to  undergo 
until  gas  begins  to  be  generated  in  it "  ;  and  it  is  really 
doubtful  whether  the  air  of  a  properly  constructed  and 
well-ventilated  sewer  can  be  shown  to  contain  a  harmful 


384   THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 

excess  of  injurious  gases  and  organisms.  However,  it  is 
essential  that  sewage  should  always  be  removed  from  the 
premises  of  a  dwelling  as  soon  as  possible  after  its  pro- 
duction and  before  decomposition  begins. 

AVhen  the  above-mentioned  constituents  of  sewage  are 
to  be  disposed  of  collectively,  the  ifater-carriage  system 
is  usually  the  best.  Although  the  pneumatic  system 
(wherein  air-tight  pipes  extend  from  the  dwellings,  etc., 
to  reservoirs  from  which  the  air  is  periodically  exhausted 
and  the  sewage  thus  drawn  into  them)  would  seem  to  be 
advantageous  where  the  topographical  conditions  do  not 
permit  of  natural  drainage,  it  is  always  subject  to  the 
danger  of  breaks  occurring  and  destroying  the  action,  and 
seems  to  have  been  practically  successful  in  but  few 
instances. 

A  modification  of  the  pneumatic  system  which  seems 
to  be  more  successful  and  practical  is  the  Shone  or  ejector 
system.  In  this  the  sewage  is  conducted  by  gravity 
through  suitable  drains  to  convenient  ejector  stations  or 
tanks,  whence  it  is  forced  by  means  of  compressed  air  to 
the  irrigation  fields  or  other  places  of  ultimate  disposal. 
The  system  has  been  in  successful  operation  in  Arad, 
Hungary,  since  1896,  the  plant  disposing  of  the  sewage 
of  20,000  persons  from  five  ejector  stations  at  a  working 
cost,  excluding  interest  and  sinking  fund,  of  about  25s. 
($6.25)  per  day.' 

On  the  other  hand,  where  house  refuse  only  is  to  be 
considered,  and  where  the  waste-water  can  be  kept  from 
the  other  parts  of  the  sewage,  or  where  the  water-supply, 
the  physical  conditions,  or  the  cost  of  constructing  the 
necessary  sewers  prevent  the  use  <»f  the  water-carriage 
method,  recourse  must  be  had  to  the  pai/  or  earth-closet 
'  American  Year-book  of  Medicine  for  1900,  pp.  549,  550. 


PAIL  SYSTEM.  385 

system.  The  use  of  primitive  privy-vaults  or  cesspools 
is  most  insanitary  and  dangerous,  and  should  be  .con- 
demned in  almost  every  instance.  Where  the  necessity 
for  one  of  the  latter  seems  imperative,  it  should  be  made 
absolutely  water-tight,  so  that  none  of  the  contents  may 
escape  to  pollute  the  surrounding  soil  and  soil-air  or  to 
contaminate  the  ground-water  in  the  neighborhood. 
Moreover,  the  pits  should  be  properly  ventilated  and 
should  be  cleaned  out  regularly  and  often,  which  may  be 
done  without  offence  by  some  form  of  odorless  excavat- 
ing apparatus,  such  as  is  now  commonly  used. 

The  daily  addition  of  a  solution  of  chlorinated  lime  or 
milk  of  lime  or  of  sulphate  of  iron,  to  the  extent  of  about 
two  quarts  for  each  person  using  the  cesspool,  will  do 
much  in  the  way  of  checking  bacterial  growth,  even 
though  it  does  not  actually  disinfect  the  contents,  and 
will  largely  prevent  the  offensive  odors  of  putrefaction 
from  such  accumulations.  It  should  be  noted  that  the 
contents  of  such  a  vault,  or  of  a  simple  pit  in  the  earth, 
undergo  putrefacticm  rather  than  natural  decomposition, 
l)ecause  of  the  lack  of  sufficient  oxygen  supply  and  of 
tlie  adjunct  action  of  the  nitrifying  bacteria  which  are 
found  only  in  the  uppermost  layers  of  the  soil. 

It  is  also  probable  that  many  disease  germs,  particularly 
those  of  diphtheria  or  typhoid  fever,  will  survive  and 
multiply  better  in  the  contents  of  such  a  vault  than  in 
sewage  or  refuse  treated  by  the  methods  to  be  hereafter 
described. 

In  the  pail  system  the  more  solid  waste  matters,  and 
especially  human  excreta,  are  collected  in  a  suitable  pail 
or  tub,  which,  holding  only  a  limited  amount,  must  of 
necessity  be  removed  and  emptied  regularly  and  often. 
If  the  outbuildings  used  for  this  purpose  be  kept  clean 

25 


386   THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 

and  properly  ventilated,  such  a  system  will  be  both 
economical  and  healthful. 

Advantage  may  here  be  taken  of  the  great  deodorizing, 
nitrifying,  and  oxidizing  power  of  fine  dry  earth,  and 
various  forms  of  eaiih-dosets  have  been  devised  to  be  used 
in  conjunction  with  the  pail  system.  If  a  quantity  of  dry, 
sifted  earth,  in  bulk  about  twice  that  of  the  dejecta,  is 
thrown  upon  the  latter  after  using  the  closet,  they  will 
be  rendered  inodorous  and  inoffensive.  For  this  purpose 
loam  and  clay  are  best,  though  sifted  ashes  may  be  used 
with  almost  as  good  results,  but  sand  or  gravel  will  not 
be  so  efficient  as  the  loam  or  ashes.  Moreover,  owing 
probably  to  the  action  of  the  nitrifying  bacteria  in  the 
earth,  all  trace  of  the  peculiar  nature  of  the  organic  com- 
pound is  quickly  destroyed,  and  the  mixture  soon  becomes 
practically  nothing  but  humus,  and  is  an  excellent  fer- 
tilizer. 

The  pail  or  earth-closet  must,  of  course,  be  separate 
and  apart  from  the  dwelling,  as  it  is  impossible  to  have 
the  same  means  of  keeping  the  gaseous  emanations  and 
effluvia  out  of  the  house  as  with  the  water-carriage 
system ;  and  it  is  also  important  that  the  liquid  house- 
slops,  wash-water,  etc.,  be  kept  separate  from  the  fecal 
waste,  which  should  be  kept  as  dry  as  possible  to  lessen 
putrefaction  and  to  increase  its  possible  value  as  a  fer- 
tilizer. Nor  sliould  this  liquid  waste  be  allowed  to  soak 
into  and  pollute  the  soil  about  the  house.  It  should 
be  collected  in  a  water-tight  reservoir,  whence  it  can  be 
removed  at  frequent  intervals,  or,  better  yet,  carried  by 
suitable  drains  to  a  kitchen  garden  or  other  land  at  a 
proper  distance  from  the  house,  and  be  there  disposed  of 
by  irrigation  or  sulj-irrigation. 

As  one  can  readily  see,  this  pail  system  is  especially 


SEWAGE-PLUMBINO  AND  HOUSE-DRAINAGE.   387 

well  adapted  to  isolated  houses  and  small  communities, 
where  each  householder  can  take  care  that  the  necessary 
details  are  properly  attended  to,  and  where,  as  is  likely, 
there  is  not  a  general  water-supply,  or  where  the  expense 
of  constructing  the  necessary  sewers  would  be  too  great. 

But  even  in  cities  as  large  as  Manchester,  England, 
"  where  four-fifths  of  the  people  are  obliged  to  have 
earth-closets,"  the  system  is  said  to  have  proved  entirely 
advantageous  and  practicable. 

Where  there  is  a  common  and  general  supply  of  water 
throughout  the  house  or  to  a  number  of  houses  there  must 
be  some  provision  for  carrying  off  the  waste-water,  and 
as  this  latter  will  have  probably  become  polluted  in  its 
use,  it  will  be  advantageous  to  utilize  it  to  remove  the 
other  sewage.  In  fact,  where  the  conditions  are  favorable 
the  water-carriage  system  will  usually  be  found  the  best 
of  all,  because  it  is  more  nearly  automatic  and  depends 
least  on  human  interference  and  efficiency. 

The  necessary  apparatus  comprises,  on  the  one  hand, 
that  which  belongs  to  the  building  and  its  premises,  viz.  : 
the  house  fixtures,  pipes,  and  drains  ;  and,  on  the  other, 
the  common  or  public  sewers  which  receive  the  sewage 
from  the  house-drains  and  convey  it  to  its  place  of  ulti- 
mate disposal. 

Sewag-e-plumbing"  and  House-drainage. 

The  essence  of  any  good  system  for  the  removal  of 
sewage  from  a  dwelling  or  building  is  simplicity.  There- 
fore, inasmuch  as  it  has  been  stated  that  sewage  should 
always  be  removed  from  the  premises  as  soon  as  possible 
after  its  production  and  before  fermentation  or  putrefac- 
tion l)egins  in  it,  it  is  evident  that  in  such  a  system  we 
should  have   for   our   object    and  provide  for :    "1.  The 


388   THE  REMOVAL  AND   DISPOSAL   OF  SEWAGE. 

speediest  possible  removal  from  the  house  to  the  public 
sewer  of  excretal  and  other  refuse  by  means  of  water.  2. 
The  prevention  of  the  deposit  of  foul  matter  in  any  part 
of  the  drainage  system  and  of  percolation  into  the  soil  of 
polluting  liquids.  3.  The  establishment  of  a  current  of 
air  through  every  part  of  the  soil-drains  and  -pipes,  in 
order  to  disperse  any  foul  gases  that  may  form  and  to 
allow  them  to  escape  with  safety  into  the  open  air.  4, 
The  prevention  of  any  entry  of  air  from  soil-pipes,  drains, 
and  waste-pipes  into  the  house.  5.  The  exclusion  of  the 
air  of  the  common  sewer  from  the  house-drains  and  the 
house;  the  last  being,  perhaps,  the  most  important,  as 
the  air  of  the  public  sewer  may  at  any  time  contain  the 
active  germs  of  specific  disease."  ^ 

The  attainment  of  the  above  requirements  is  to  be 
secured  in  the  manner  to  be  described.  The  soil-pipe  is 
that  which  receives  the  sewage  from  water-closets  and, 
usually,  from  the  waste-pipes  of  other  fixtures,  such  as 
bath-tubs,  wash-stands,  sinks,  etc.,  and  which  connects 
them  with  the  house-drain ;  the  latter  is  the  conduit 
connecting  the  soil-pipe  Mith  the  sewer.  Waste-pipes 
convey  the  contents  of  wash-stands  and  other  fixtures  to 
the  soil-pipes  or  to  a  branch  of  the  house-drain.  (See 
Fig.  64). 

The  soil-pipe  is  usually  located  almost  entirely  within 
the  house,  although,  were  it  not  for  the  danger  of  its  con- 
tents freezing,  it  would  be  better  to  have  it  fastened  to 
the  wall  outside.  It  is  made  of  cast  or  wrought  iron, 
should  be  at  least  four  inclies  in  diameter,  sliould  convey 
the  sewage  as  directly  as  possible  from  the  fixtures  to  the 
house-drain,  and  must  extend  unobstructed  from  the  latter 
to   several  feet  above  tlie  roof,  ending  where  winds  and 

*  L.  C.  Parkcs,  Hygiene  and  Public  Health,  2d  edition,  p.  139. 


SOIL-PIPE. 


389 


currents  from  high  "U'alls  and  chimneys  will  not  interfere 
with  its  free  ventilation.     Every  branch  of  the  soil-pipe 


Fig.  64. 


Illustrating  sewage-plumbin<?  of  a  house.    The  traps  of  the  rain-leaders  at 
their  junctions  with  the  house-drain  have  been  accidentally  omitted. 

more  than  eight  feet  in  length,  or  to  wliich  two  or  more 
water-closets  are  connected,  should  also  be  extended  above 


390    THE  REMOVAL  A^D  DISPOSAL   OF  SEWAGE. 

the  roof,  or  else  be  extended  and  connected  to  the  main 
soil-pipe  above  the  highest  fixture  connected  therewith, 
as  there  must  be  no  closed  ends  wherein  foul  or  stagnant 
air  may  collect.  All  joints  must  be  absolutely  air-tight, 
and  the  pipe  must  be  so  secured  that  any  vibration  or 
settling  of  the  building  will  not  be  likely  to  destroy  its 
continuity.  In  new  buildings,  especially,  all  soil-pipes 
should  be  exposed  or  else  covered  in  with  panels  easily 
removable  at  any  time  to  permit  of  inspection  or  repaii'S. 
Any  hidden  pipes  or  those  difficult  of  access  should  be 
of  extra  heavy  materials,  and  extra  care  should  be  given 
to  the  joints  and  supports.  The  soil-pipe  and  house-drain 
should  both  be  as  smooth  as  possible  interiorly,  and  in  the 
construction  they  must  be  carefully  inspected  to  prevent 
anv  of  the  material  used  in  caulkino^  or  cementino;  the 
joints  from  projecting  within  to  prevent  the  free  flow 
of  sewage. 

Outside  of  the  house  the  house-drain  may  be  of  iron  or 
of  glazed  and  impervious  earthenware,  but  no  earthen  pipe 
should  be  permitted  within  five  feet  of  a  foundation  wall, 
and  where  any  part  of  the  house-drain  is  within  the  build- 
ing it  should  Ije  of  iron  and  securely  fastened  to  the 
foundation- wall  above  the  cellar  floor.  The  connection 
Ijctween  it  and  any  soil-pipe  should  l)e  by  means  of  a 
rounded  elbow,  and  not  by  an  abrupt  right  angle.  (Fig. 
65).  The  house-drain  should  not  be  less  than  four  nor 
more  than  ten  inches  in  diameter,  should  be  laid  on  a 
firm  foundation,  should  have  air-tight  joints,  and  should 
have  a  slope  toward  the  sewer  of  at  least  one-half  inch  to 
the  foot. 

If  a  house-drain  emjity  into  a  sewer  of  the  "combined" 
system,  there  must  l)e  a  trap  just  before  its  junction  Avith 
the  sewer  to  prevent  the  passage  of  sewer-air  back  into 


HOUSE-DRAIN. 


391 


the  house  (Fig.  66),  and  there  must  also  be  an  opening  for 
fresh  air  between  this  trap  and  the  house-drain,  so  that 
there  may  be  a  constant  current  of  air  throus:h  the  house- 


FiG.  65. 


Method  of  connecting  soil-pipe  with  house-drain. 

drain  and  soil-pipes  to  the  exit  above  the  roof,  and  the 
air  in  the  soil-pipes  thus  kept  from  becoming  foul  and 

Fig.  66. 


Main  trap  to  be  placed  between  sewer  and  cesspool,  or  between  house-drain 
and  main  sewer.    (Notter  and  Firth.) 


stagnant.  But  if  the  house-drain  empties  into  a  sewer 
of  the  "  separate  "  system,  there  need  be  no  trap  between 
the  drain  and  sewer,  for  reasons  to  be  hereafter  stated; 


392    THE  REMO  VAL  AND  DISPOSAL    OF  SEWAGE. 

however  the  fresh-ah'  inlet  between  sewer  and  house-drain 
is  always  advisable,  as  it  tends  further  to  assist  ventilation. 

A  house-drain  should  not  empty  into  a  cesspool  unless 
it  is  absolutely  necessary,  and  in  such  case  the  cesspool 
must  be  well  ventilated  and  also  separated  from  the  drain 
by  a  fresh-air  inlet  and  trap,  just  as  when  the  drain  emp- 
ties into  a  combined  sewer.  Nor  should  any  cesspool 
empty  into  a  sewer. 

Where  rain-water  conductors  empty  into  house-drains 
or  sewers,  they  should  be  separated  from  the  latter  by 
traps  having  a  seal  of  not  less  than  five  inches,  to  prevent 
sewer-air  passing  up  through  them  to  the  vicinity  of  win- 
dows, etc.  So,  also,  all  waste-pipes  and  other  pipes  open- 
ing into  house-drains  should  be  trapped. 

In  the  house  all  water-closets  and  other  fixtures  should 
be  as  near  the  soil-pipe  as  possible  that  there  may  be  no 
long  stretches  of  foul  waste-pipe  underneath  the  floors, 
and  all  connections  with  the  soil-pipe  should  be  made  at 
an  acute  angle  that  the  discharge  into  the  latter  may  not 
interfere  with  its  free  ventilation.  Each  fixture  must  be 
separately  trapped,  and  the  trap  must  be  located  as  near  its 
fixture  as  possible.  There  must  be  no  connection  between 
a  fixture  and  the  soil-pipe  or  house-drain  which  is  not 
trapped. 

A  little  reflection  will  show  that  by  observing  the  above 
rules  of  construction  provision  will  have  been  made  for 
each  of  the  five  specified  requirements  of  the  system,  and 
the  air  in  the  soil-pipes  will  be  almost  as  pure  as  that  of 
the  house  itself.  The  absorption  of  foul  gases  by  the 
water  in  the  house-traps  and  their  subsequent  dispersion 
into  the  atmosphere  of  the  house  will  also  be  almost 
impossible.  But  there  must  always  be  free  communica- 
tion between  the  air  inlet  into  the  house-drain  and  the 


TEA  PS  FOE  SEWER-GAS. 


393 


outlets  from  and  at  the  top  of  the  soil-pipes  ;  otherwise 
the  air  in  the  soil-pipe  cannot  be  changed  and  foul  gases 
will  accumulate  which,  by  their  pressure,  would  tend  to 
force  themselves  into  the  house  whenever  an  opportunity 
occurred,  and  might  even  overcome  the  seal  of  some  of 
the  traps. 

Traps  are  "appliances  placed  between  house  conve- 
niences (fixtures)  and  soil-pipes  and  drains  or  sewers,  to 
prevent  sewer-gas  gaining  an  entrance  into  the  house," 
Most  traps  are  too  complicated.     The  simpler  a  trap  the 


Fig.  67. 


Fig.  68. 


These  illustrations  show  how  a  uniform  calibre  prevents  the  accumulation 
of  dirt  in  a  trap,  and  how  angles  and  corners  favor  such  accumulations. 
(Gerhard.) 

better,  provided  it  have  sufficient  seal.  The  seal  of  a 
trap  is  the  depth  of  water  or  the  mechanical  appliance 
which  prevents  the  back-flow  of  gas.  Mechanical  appli- 
ances are  liable  to  become  clogged  and  not  to  fit  tightly, 
thus  allowing  the  passage  of  sewer-air ;  they  also  tend  to 
check  the  free  onward  flow  of  the  sewage,  thus  favoring 
deposition  in  and  preventing  the  cleansing  of  the  trap. 
The  S  or  siphon  trap  is  as  simple  as  any,  is  of  uniform 
diameter  throughout,  has  no  corners  or  projections  to 
catch  dirt,  and  is  thoroughly  cleansed  by  each  fair  flow 
of  water  through  it.     The  value  of  a  trap  does  not  depend 


394   THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 


so  much  on  the  amount  of  water  it  contains  as  on  the 
depth  or  strength  of  the  seah  On  account  of  evaporation 
the  water-seal  of  a  trap  may  become  lessened  or  de- 
stroyed unless  the  fixture  to^  which  it  is  attached  be  in 

Fig.  69.  Fig.  70. 


S  or  siphon  trap,  with  opening  for 
ventihxtion-pipe.     (Gerhard.) 


Bell  trap.    (Gerhard.) 


frequent  use ;  it  is  therefore  advisable  to  have  as  few 
fixtures  of  any  kind  in  the  house  as  the  comfort  or  con- 
venience of  the  inmates  will  allow.  So,  also,  if  a  house 
is  to  be  unoccupied  for  a  time,  it  is  well  to  cover  the 
water  in  the  traps  with  oil  or  glycerin  to  prevent  evapo- 


FiG.71. 


Fig.  72. 


Ciidell's  trap.    (Gkrhard.) 


Bower's  trap.    (Gerhard.) 


ration  of  the  former.  Tjcakagc  or  capillary  action,  the 
latter  caused  by  ae(ninuilations  of  hair,  thread,  etc.  in  the 
trap,  may  lil<<>wise  lower  the  water  so  that  sewer-gas  may 
pass  through  from  the  soil-pipe. 


ANTI-SIPHOmNG   ATTACHMENT. 


395 


Lastly,  the  seal  of  a  trap  may  be  broken  by  siphonage, 
either  by  a  strong  rash  of  water  through  it  from  its  own 
fixture,  or  by  a  rush  clown  the  soil-pipe  from  a  fixture 
higher  up,  and  this  is  especially  liable  to  occur  if  the  trap 
be  some  distance  from  the  soil-pipe,  or  if  the  fixtures  above 
discharge  a  large  amount  of  water  at  once.  To  prevent 
this,  openings  are  sometimes  made  at  the  top  of  the  traps 
on  the  side  next  the  waste-pipe  or  soil-pipe  and  con- 
nected with  vent-pipes,  which  should  open  into  the  soil- 

FiG.  73. 


Grease  trap.    (Harrington.) 

pipe  above  the  entrance  of  the  waste-pipe  from  the  highest 
fixture,  or  be  continued  separately  into  the  out-door  air. 
(See  Fig.  64.)  But  this  greatly  increases  the  expense,  and, 
as  the  vent-pipes,  to  be  efficient,  must  be  almost  two  inches 
in  diameter,  they  also  favor  evaporation  from  the  trap. 
If  the  trap  is  properly  constructed,  if  the  soil-pipe  is  of 
suitable  size  and  heiglit,  and  if  the  fixtures  be  placed 
as  near  the  soil-pipe  as  possible,  there  will  be  but  little 


396    THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 

danger  of  siphonage  occurring.  Where  it  does  occur, 
INIeClellan's  anti-siphon  attachment  (Fig.  74)  is  said  to 
work  advantageously,  being  inexpensive  and  permitting 
a  free  ingress  of  air  to  the  trap,  but  no  egress  of  air  from 
the  soil-pipe  into  the  house.  In  this  device  a  small 
weighted  and  inverted  cup  rests  with  its  edge  immersed 
in  a  ring  of  mercury,  from  which  it  is  raised   by  the 

Fig.  74. 


McClellan's  anti-siphon  attachment.    Sectional  view  of  vent  with  cnp  lifted 
out  of  the  mercury  by  the  inflowing  current  of  air,  indicated  by  the  arrows. 

(ROHfe.) 

atmospheric  pressure  only  when  the  siphonage  sufficiently 
reduces  the  pressure  within  the  pipes.  The  mercury  and 
the  weight  of  the  cup  make  a  seal  sufficient  to  prevent 
any  outflow  of  gas.  It  is  also  said  that  if  the  waste- 
])ipc  be  connected  with  the  soil-pipe  by  a  divergent  open- 
ing, sij)]ioiiago  will  be  less  likely  to  occur. 

All  waste-pipes,  soil-pipes,  and  house-drains  should  be 


TESTING    OF  PIPES  AND  DRAINS. 


397 


tested  before  use  by  closing  all  openings  and  forcing  in 
air  to  a  pressure  of  at  least  thirty  pounds  to  the  square 


inch.     Leaks    may  be   detected   by   plugging   the    lower 
openings  and  filling  the  pipes  with  water,  or  by  ]>ouring 


398    THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 

an  ounce  of  oil  of  peppermint  into  the  highest  fixture  and 
quickly  following  this  with  several  gallons  of  hot  water, 
the  heat  volatilizing  the  oil,  whose  odor  escapes  at  every 
opening  in  the  pipes  unprotected  by  a  trap  or  water-seal. 
The  heat  imparted  by  the  hot  water  w^ll  also  help  to  trace 
out  hidden  soil-pipes. 

All  fixtures  should  be  exposed  to  the  free  ventilation 
of  air  underneath  and  about  them,  and  water-closets  and 
wash-stands  should  not  be  closed  in  with  carpentry  w^ork. 
(See  Fig.  75).     Traps  should  also,  if  possible,  be  where 

Fig.  76. 


Wash-basin  with  overflow  horn  discharginfi;  beneath  plug.    (Harrington.) 

they  may  be  opened  and  inspected  at  any  time.  Under 
each  closed-in  fixture,  if  there  must  be  such,  there  should 
be  a  drip-safe  to  catch  any  leakage  or  overflow  of  water, 
but  the  pipes,  if  any,  leading  from  these  should  never 
em])ty  into  waste-pipes  or  soil-pipes  ;  they  should  lead 
preferably  into  the  open  air  and  not  to  the  cellar,  as  tlie 
cellar-air,  which  is  usually  imj)ure,  tlius  gains  access  to  the 
house.  Even  if  these  drip-safe  pipes  are  trapped  and  open 
into  the  soil-pipe,  the  water  in  the  trap  is  replenished  so 
rarely  that  evaporation  soon  destroys  the  seal  and  allows 
the  air  to  pass  from  the  soil-pipe  into  the  house. 


WATER-CLOSETS. 


399 


The  overflow-pipe  of  old-fashioned  wash-stands  and 
bath-tubs  is  objectionable,  as  it  collects  dirt  of  all  kinds, 
soap,  epithelium,  etc.,  and  it  is  almost  impossible  to  clean 
it.  Beside,  it  will  often  be  found  opening  into  the  waste- 
pipe  below  the  trap,  thus  allowing  the  free  passage  of 
sewer-air  into  the   room.     When  new  fixtures  are  being 

Fig.  77. 


Improved  stand-pipe  overflow.    (Harrington.) 


put  in  they  should  preferably  be  such  as  make  use  of  the 
stand-pipe  principle  in  the  stoppers  and  that  have  no 
separate  or  concealed  overflow-pipe  or  outlet. 

Water-closets. — The  requisites  for  a  good  water-closet 
are :  that  it  does  not  allow  the  escape  of  sewer-air  from 
the  soil-pipes  into  the  house ;  that  it  is  thorougldy  and 
easily  cleaned   each   time   after  use ;    that  there   are    no 


4C0   THE  REMOVAL   AXD  DISPOSAL   OF  SEWAGE. 

hidden  parts  in  which  tilth  can  collect,  or  which  cannot 
be  readily  cleaned ;  that  the  flushing  or  washing  out  of 
the  closet  be  done  in  such  a  way  that  dirt  or  spray  be  not 
thrown  intri  the  air  of  the  room  ;  that  there  be  sufficient 
water-supply  to  wash  out  the  bowl  and  trap  each  time  and 
to  refill  them  to  the  proper  level ;  that  the  trap  itself  is  not 
siphoned  or  left  empty  by  a  discharge  of  water  from  this 
or  another  tixiure. 

Fig.  78. 


Pan  closet.    ^Geehaed.^ 

Of  the  ditFereut  kinds  of  water-closets  the  pan  and  the 
valve  closets  are  the  oldest  and  tlie  worst,  and  should  not 
be  used.  They  consist  of  a  receiving  bowl,  the  bottom  of 
which  opens  into  a  swinging  pan  or  is  closed  by  a  valve. 
The  pan  or  valve  and  the  lower  part  of  the  receiving  bowl 
are  enclosed  in  anntlier  bow],  tlie  container,  connected 
with  the  soil-pipe  and  trap.  The  depth  of  water  in  the 
receiving  Ijowl  in  \xin  closets  is  regulated  by  the  depth  of 
the  pan,  and  in  valve  closets  by  the  location  of  an  overflow 
outlet.  In  l)oth  kinds  the  contents  of  the  receiving  Ixtwl 
are  discharged  into  the  container  by  the  tipping  of  the 


PLUNGER   CLOSETS. 


401 


pan  or  valve,  aud  consequently  the  sides  of  the  con- 
tainer, as  well  as  the  under  side  of  the  pan  or  valve,  soon 
become  thickly  coated  vrith.  filth.  This,  being  hidden, 
accumulates,  decomposes,  and  contaminates  the  air  in  the 
container,  which  air  is  of  necessity  discharged  into  the 
room  as  often  as  it  is  displaced  by  the  contents  of  the 
receiving  bowl.  In  valve  closets  the  overflow-pipe  from 
the  receiver  furnishes  an  additional  way  by  which  the 
foul  air  may  pass  from  the  container  into  the  atmosphere 

Fig.  79. 


Valve  closet.    (Geehaed.) 

of  the  room.     It  needs  no  argument  to  show  that  these 
closets  are  decidedly  dangerous  to  health. 

Plug  or  plunger  closets  are  those  in  which  the  outlet 
above  the  trap  is  sto])pered  by  a  plunger,  this  being  usu- 
ally in  a  chamber  at  the  side  of  the  receiving  bowl.  The 
bowl  and  side  chamber  liolding  a  considerable  quantity  of 
water,  the  trap  is  well  flushed  out  each  time  of  use  ;  but 
the  side  chamber  and  plunger,  being  hidden  and  not  easily 
cleaned,  soon  become  coated  with  filth  and  dangerous  to 

26 


402    THE  REMOVAL  AND  DISPOSAL    OF  SEWAGE. 


health,  as  there  is  nothing  to  prevent  the  air  from  passing 
from  this   chamber  into   the  room.     Moreover,  the  plug 

Fig. 


£rr:??^VV}^^W->>v\ 


^■•-y,-^.;-:fflWi 


•i/^i,v/,-Y^--^,/fr^'*-f,?/^ 


V'^,?"f!^^mm 


Plug  or  plunger  closet.    (Gerhard.) 

may  not  close  the  opening  completely,  thus  allowing  a 
continual  waste  of  water,  A  trapped  overflow-pipe  in 
the  plunger  keeps  the  closet  from  overflowing. 

Fig.  81. 


f^tf^m. 


(?XWii'/i^r;^',-W^m 


Short-hopper  closet.    (Gerhard.) 

TTo]>pcr  closets  consist  simply  of  a  bowl  connected  below 
with  an  ordinary  trap,  and,  as  there  is  nothing  to  get  out 


WASH-OUT  AND  SIPHON  CLOSETS. 


403 


of  order,  this  kind  is  theoretically  one  of  the  best.  The 
objection  to  long  hoppers  is  that  dirt  is  apt  to  stick  to  the 
sides  and  become  offensive,  but  this  can  be  prevented  if  it 
is  so  arranged  that  water  begins  to  flow  down  the  sides  as 
soon  as  the  closet  is  put  to  use,  thus  preventing  adhesion. 
Short  hoppers  have  not  this  objection,  as  the  feces  fall 
directly  into  the  water  in  the  bowl  and  are  carried  out 
through  the  trap  as  the  bowl  is  flushed.  All  water-closets 
should  have  a  flushing  rim  encircling  the  top,  so  that  all 
sides  of  the  bowel  may  be  washed  down  and  cleansed  each 
time  the  closet  is  used. 


Ficx.  82. 


Fig.  83. 


Wash-out  water-closet.    (Parkes.)  Dececo  siphon  closet.    (Parkes.) 


Wash-out  closets  retain  considerable  water  in  the  bowl, 
and  are  emptied  by  a  strong  flush  of  water  from  the  flush- 
ing rim.  They  are  simple,  do  not  readily  get  out  of  order, 
and  are  much  in  favor  at  the  present  time.  As  they  are 
a  modification  of  the  short-hopper  closet,  so  is  the  siphon 
closet  a  modification  of  the  wash-out  variety. 

In  the  siphon  closet  the  contents  of  the  bowl  and  trap 
are  lifted  out  by  siphonic  action,  and  then  the  bowl  and 
trap  are  refilled,  as  in  the  case  of  wash-out  closets,  by  an 
after-flush.  In  the  Dececo  closet — a  siphon  closet— use 
is  made  of  the  principle  involved  in  the  Field  flush-tank. 


404    THE  REMOVAL  AND  DISPOSAL    OF  SEWAGE. 

Hopper,  wash-out,   and   siphon  closets  should  be  sup- 
plied from  water-closet  cisterns,  which  should  give  a  cer- 

FiG.  84. 


Sanitas  siphon  closet.    (Harrington.) 

tain  and  sufficient  volume  of  water  with  only  a  short 
pull  on  the  chain.  The  bowl  and  trap  should  also  be 
automatically  refilled  from  the  cistern  after  use. 

Water-closets  should  not  be  connected  directly  with  the 
water-supply  pipes  of  the  house,  as  air  from  the  closets 
may  be  sucked  into  them  at  times  when  the  water-supply 
is  cut  off,  and  the  water  afterward  contaminated  by  it. 
But  this  is  difficult  to  avoid  in  pan,  valve,  or  plug  closets, 
and  is  another  serious  objection  to  their  use. 

Vent-pipes  from  the  bowl  and  seat  of  water-closets 
must  1)0  large,  and  must  not  open  into  the  soil-pipe,  but 
into  the  ojien-air  ;  they  must  not  open  near  a  window  nor 
any  place  from  which  air  is  taken  into  the  house,  but  may 
open  into  a  flue  which  is  constantly  heated,  as  a  kitchen 
chimney,  or  may  themselves  be  heated  and  have  a  current 
maintained  in  them  by  a  small  lamp  or  gas-jet.  In  this 
way  the  room  in  which  a  water-closet  is  located  may  be 
effectively  ventilated. 

\Vater-closets  should  never  be  placed  in  dark  closets, 


SEWEBS.  405 

nor  in  bed-rooms  or  living-roomSj  but  should  always  be 
in  separate  rooms  that  have  free  communication  with  the 
open  air  by  means  of  a  large  window  or  by  a  ventilating 
shaft  of  at  least  four  square  feet  sectional  area  throughout 
its  length.  It  is  also  advisable  that  bed-rooms  should 
not  communicate  directly  with  bath-rooms,  etc.,  con- 
taining water-closets,  unless  there  is  every  assurance  that 
the  closet  and  plumbing  connected  with  it  are  first-class 
in  every  particular. 

It  will  not  be  out  of  place  to  suggest  in  this  connection 
that  apparatus  for  household  conveniences,  such  as  wash- 
stands,  bath-tubs,  water-closets,  kitchen  sinks,  etc.,  which 
satisfies  every  practical  sanitary  requirement  can  now  be 
had  at  prices  that  are  quite  reasonable  when  the  necessary 
care  and  scientific  experience  in  construction  are  taken 
into  consideration.  The  advance  has  been  in  the  reduc- 
ing of  the  number  of  parts  in  an  article,  some  being  now 
made  in  a  single  piece,  thus  lessening  or  eliminating  the 
crevices  that  would  collect  and  hold  dangerous  filth ; 
likewise  concealed  overflow  pipes  and  corners  and  de- 
pressions difficult  to  clean  have  been  done  away  with ; 
and  a  third  gain  has  been  in  the  substitution  of  solid 
vitrified  or  enameled  metal  ware  for  articles  that  were 
made  of  comparatively  soft  substance  and  with  a  glazed 
surface  that  was  liable  to  crack  and  thus  permit  the 
absorption  of  foul  matters  and  possibly  harmful  organ- 
isms. That  these  advantages  have  also  been  accom- 
panied by  an  advance  in  aesthetic  appearances  is  well 
demonstrated  by  the  illustration  on  page  397,  or  by 
what  may  be  seen  in  almost  any  well-equipped  modern 
dwelling. 

Sewers. — These  are  the  conduits  provided  to  receive 
and   convey    the  contents   of     house-drains    and    other 


406    THE  FF-MOVAL   AND   DISPOSAL    OF  SEWAGE. 

drains  to  tlie  place  of  final  disposal  or  discharge.  They 
may  be  of  either  of  two  kinds — combined  or  separate. 
Sewers  of  the  first  class,  which  have  heretofore  been 
most  commonly  used  in  this  country,  are  constructed  to 
carry  off  all  kinds  of  sewage,  the  waste  liquids,  etc.  from 
factories,  street-washings,  and  the  surplus  rain-water  of 

Fig.  85. 


Section  of  ovoid  sewer  of  "  combined  "  system. 

the  district  drained  by  them.  As  this  necessitates  a  size 
and  capacity  sufficient  to  receive  the  greatest  probable 
rainfall  upon  the  area  drained  in  addition  to  the  other 
sewage,  it  is  evident  that  the  depth  of  the  usual  daily  vol- 
ume of  the  latter  in  the  sewer  will  be  so  shallow  and  the 
current  so  sluggish  as  greatly  to  favor  the  settling  of  the 


SEWERS   OE  THE  SEPARATE  SYSTEM.  407 

solid  and  semisolid  constituents,  the  obstruction  of  the 
sewers,  and  the  development  of  bacteria  and  sewer-gas. 
To  obviate  these  faults  and  to  insure  a  more  rapid  flow  by 
keeping  the  depth  of  sewage  as  great  as  possible,  the 
smaller  conduits  at  least  are  generally  made  ovoid  in  sec- 
tion, the  smaller  end,  of  course,  being  downward.  Com- 
bined sewers  are  not  only  more  expensive  to  construct  and 
to  keep  in  repair  than  those  of  the  separate  system,  but 
greater  care  must  be  had  to  see  that  they  are  at  all  times 
properly  ventilated.  The  main  advantage  claimed  for 
them  is  that  the  expense  of  constructing  separate  conduits 
for  factory  wastes,  street- washings,  and  the  excess  of  rain- 
water is  avoided ;  but  this  is  a  doubtful  one  both  in  respect 
to  economy  and  sanitation. 

The  ventilation  of  sewers  of  this  kind  is  usually  suffi- 
ciently provided  for  by  the  inlets  for  street-washings  and 
rain-water,  located  at  street-corners,  etc.  ;  but  if  these  are 
not  close  enough  together  to  keep  the  sewer  atmosphere 
constantly  changing  and  reasonably  pure,  other  ventila- 
tion openings  should  be  made.  But  in  all  cases  the  air 
from  sewers  of  the  combined  system  must  be  excluded 
from  house-drains,  etc.,  by  the  traps  which  have  been 
described. 

Only  the  sewage  proper  from  dwellings,  and  occasionally 
from  small  factories,  is  admitted  to  the  sewers  of  the 
separate  system,  the  rain-waters,  surface-waters,  and 
soil-waters  being  removed  by  other  drains  or  channels. 
The  advantages  of  this  system,  which  is  now  indorsed 
by  almost  all  sanitarians,  are  that  the  volume  of  sewage 
to  be  carried  is  comparatively  small  and  constant,  and  that 
it  can  be  calculated  very  approximately  from  the  daily 
water-supply  and  population  ;  that  the  cost  of  construc- 
tion is  much  less  than  that  of  sewers  of  the  combined 


408    THE  REMOVAL  AND   DISPOSAL   OF  SEWAGE. 

system,  and  that,  while  it  is  available  and  satisfactory 
for  large  cities,  it  is  the-ouly  one  that  small  communities 
would  consider  or  can  afford ;  that  the  sewage  is  more 
concentrated  and  uniform  in  composition,  and  can  thus 
be  better  utilized  as  a  fertilizer  or  disposed  of  in  whatever 
manner  may  be  most  sanitary  and  advantageous ;  that  the 
sewers,  having  smaller  peripheries  and  smoother  walls,  are 
more  frequently  and  effectually  flushed,  and  that  they  are 
more  completely  ventilated  and  altogether  better  suited  to 
the  work  to  be  performed.     The  disadvantages  of  sewers 

Fig.  86. 


Field's  annular  siphon  flush-tank.    (Paekes.) 

of  this  class  are  that  a  community  must  have  two  sets  of 
drains,  one  for  sewage  and  tlie  other  for  rain,  street,  and 
factory  waters,  and  that  after  a  ]>r<»tracted  dry  season  the 
street-washings,  etc.,  may  be  very  foul  ;  but  these  are  out- 
weighed by  the  advantages  above  mentioned. 

"No  sewer  of  this  system  should  be  more  than  six 
inches  in  diameter  until  it  and  its  branches  have  accumu- 
lated a  sufficient  flow  at  tlie  hour  of  greatest  use  to  fill 
this  size  half-full,  because  the  use  of  a  larger  size  is  waste- 
ful and  because  ventilation  Ijecomes  less  complete  as  the 


FOUNDATION  OF  SEWERS.  409 

size  increases.  The  size  should  be  increased  gradually 
and  only  so  rapidly  as  is  necessary  by  the  filling  of  the 
sewer  half-full  at  the  hour  of  greatest  flow ;  and  the 
upper  end  of  each  branch  sewer  should  be  provided  with 
an  automatic  flush-tank  (Fig.  86)  of  sufficient  capacity  to 
secure  the  thorough  daily  cleansing  of  so  much  of  the 
conduit  as  from  the  limited  flow  is  liable  to  deposit  solid 
matters  by  the  way." 

There  should  ordinarily  be  no  traps  between  house7 
drains  and  sewers  of  the  separate  system,  since,  having 
no  rain-water  inlets,  the  latter  would  otherwise  have  no 
openings  for  ventilation.  Moreover,  since  the  "separate" 
sewers  are  so  regularly  and  thoroughly  flushed,  the  air  in 
them  is  not  likely  to  be  so  impure,  and  there  is  not  the 
same  reason  for  excluding  it  from  the  house-drains,  etc., 
as  there  is  regarding  the  air  from  "  combined "  sewers. 
The  junction  of  house-drains  with  sewers  of  the  separate 
system  should  be  by  divergent  openings,  so  that  the  air 
may  pass  freely  into  the  drain  as  the  sewage  empties  into 
the  sewer. 

Should  one  desire,  however,  to  separate  his  house-drain 
from  the  public  sewer  by  means  of  a  trap,  and  thus  pre- 
vent the  ingress  of  sewer-air  into  his  premises,  the  venti- 
lation of  the  sewer  can  be  secured  by  providing  a  vent- 
pipe  between  the  trap  and  the  sewer.  But  in  no  case 
must  the  inlet-pipe  for  air  on  the  other  side  of  the  trap, 
between  it  and  the  house,  be  omitted ;  nor  should  the  two 
air-pipes  be  so  near  together  that  air  from  the  former  will 
be  likely  to  be  drawn  into  the  latter. 

All  sewers  should  be  laid  on  a  good  foundation  with 
sufficient  fall  to  give  at  least  a  velocity  of  two  feet  ])er 
second  to  the  flow.  If  made  of  brick,  they  should  be 
laid  in  a  mortar  made  of  cement  and  sharp  sand,  and  all 


410   THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 

sewers  should  be  as  smooth  as  possible  inside  to  prevent 
the  arrest  of  particles  of  sewage.  Sewers  of  the  com- 
bined system  should  not  be  pervious  to  the  soil-water,  as 
the  liquid  sewage  is  just  as  apt  to  pass  from  them  to  the 
soil  and  to  pollute  it  dangerously  as  the  soil-water  is  to 
pass  into  the  sewers.  But  the  rain-water  drains  of  the 
separate  system  may  also  be  employed  to  drain  the  subsoil. 

The  ultimate  disposal  of  sewage  is  a  matter  of  con- 
siderable importance  which  commonly  does  not  receive 
the  attention  it  deserves.  The  usual  method  in  this  coun- 
try of  discharging  the  sewage  into  a  running  stream  is 
reprehensible,  because  the  natural  purification  of  a  water 
thus  contaminated  must  always  be  slow  and  more  or  less 
uncertain,  and  because  the  risk  to  those  using  the  polluted 
water  must  be  a  constantly  increasing  one.  AYhere  the 
district  drained  and  supplied  by  the  stream  is  a  sparsely 
settled  one,  and  where  the  volume  of  fresh  or  running 
water  is  very  large  in  proportion  to  the  quantity  of  pol- 
lution it  receives,  the  objections  to  the  disposal  of  sewage 
in  this  way  may  seem  to  be  theoretical  rather  than  prac- 
tical ;  but  as  the  population  increases  and  the  ratio  of  pure 
water  to  filth  decreases  beyond  certain  limits,  the  question 
becomes  more  serious  and  pertinent.  It  is  said  that  to  dilute 
safely  the  sewage  of  1000  persons  requires  from  two  to 
four  million  gallons  of  unpolluted  water  per  day;  this,  of 
course,  not  destroying  the  disease  germs  nor  eliminating 
the  danger  of  their  multiplication. 

Other  methods  of  sewage  disposal  resemble  closely 
those  already  described  for  the  purification  of  water,  in 
that  they  make  use  of  subsidence,  chemical  treatment, 
and  filtration.  The  sewage  may  be  collected  in  large 
tanks,  with  or  without  the  addition  of  certain  chemicals, 
such  as  lime,  alum,  or  sulphate  of  iron,  to  increase  the 


THE   ULTIMATE  DISPOSAL   OF  SEWAGE.        411 

precipitation,  and  tlie  suspended  impurities  allowed  to 
settle  to  the  bottom  of  the  tanks,  whence  they  can  be 
removed,  squeezed  partially  dry  in  hydraulic  presses,  and 
either  disposed  of  as  a  fertilizer  or  cremated.  The  clear 
effluent  or  liquid  part  of  the  sewage  may  be  allowed  to 
flow  at  once  from  the  settling  tanks  into  a  convenient 
watercourse,  provided  it  is  there  well  diluted,  or  it  may 
better  be  filtered  through  an  area  of  porous  soil  or  through 
prepared  filter-beds.  If  the  filtration  is  properly  done,  the 
filtrate  will  contain  nothing  harmful,  and  may  be  allowed 
to  flow  where  it  will  without  danger.  A  properly  pre- 
pared filter-bed  of  twelve  inches  of  sand  upon  eighteen 
inches  of  gravel  or  magnetic  carbide  of  iron,  with  an  area 
of  one  acre,  is  said  to  be  able  to  purify  from  one  to  two 
million  gallons  of  clarified — effluent — sewage  in  twenty- 
four  hours. 

Chemical  treatment  ^v\]l  probably  cost  from  thirty-five 
to  fifty  cents  or  more  per  annum  per  individual  of  the 
population  supplying  the  sewage,  but  an  even  more 
important  question  than  cost  is  whether  the  addition  of 
the  chemicals  may  not  interfere  with  the  natural  biologic 
processes  of  purification  constantly  taking  place  in  most 
sewage.  Chemicals  that  are  or  have  been  used  as  pre- 
cipitants  are  lime,  lime  with  sulphate  of  iron,  alum,  or 
alkali  waste,  sulphate  or  iron  alone,  and  a  combination  of 
alum,  charcoal,  and  clay.  The  precipitate  obtained  with 
the  latter  makes  a  superior  fertilizer. 

Sewage  may  also  be  disposed  of  by  intermittent  down- 
ward filtration,  either  through  specially  constructed  filter- 
beds  or  a  prepared  area  of  soil ;  by  irrigation  or  sub- 
irrigation,  and  by  the  so-called  septic-tank  method. 

For  sewage,  intermittent  filtration  is  superior  to  the 
continuous   process — in  fact,  is  almost  essential,  as   the 


412    THE  REMOVAL  AND  DISPOSAL    OF  SEWAGE. 

interruption  in  the  percolation  permits  a  renewal  of  the 
air-supply  in  the  filtering  medium  or  soil,  and  thus  fur- 
nishes a  sufficient  quota  of  oxygen  for  the  oxidation  and 
nitrification  of  the  excessive  amount  of  organic  matter  in 
the  sewage.  With  sufficiently  frequent  intermittence,  fine 
sand,  such  as  is  used  for  building  purposes,  makes  an 
excellent  artificial  filter,  capable,  it  is  stated,  of  purifying 
50,000  gallons  of  crude  sewage  per  acre  per  day  and  of 
removing  all  the  solids,  much  of  tlie  dissolved  matters,  and 
99  per  cent,  of  the  contained  bacteria.  Where  the  crude 
sewage  is  allowed  to  settle  or  is  treated  biologically  in  the 
septic  tanks,  a  much  greater  quantity  of  the  clarified 
effluent  can  be  filtered  daily,  as  has  been  indicated. 

By  intermittent  soil  filtratio7i  we  mean  "  the  concentra- 
tion of  sewage  at  short  intervals,  on  an  area  of  specially 
chosen  porous  ground,  as  small  as  will  absorb  and  cleanse 
it ;  not  excluding  vegetation,  but  making  the  produce  of 
secondary  importance.  The  intermittency  of  application 
is  a  sine  qua  non  even  in  suitably  constituted  soils  where- 
ever  complete  success  is  aimed  at."  ^  The  land  should  be 
levelled  and  under-drained  with  tile  drains  at  the  depth  of 
five  or  six  feet,  and  should  be  divided  into  four  parts,  no 
part  to  receive  sewage  for  more  than  six  hours.  An  acre 
of  properly  prepared  soil  will  thus  dispose  of  the  crude 
sewage  of  1000  to  2000,  or  the  clarified  sewage  of  5000 
people. 

The  soil  to  be  used  for  this  purpose,  as  well  as  that  for 
irrigation  and  sub-irrigation,  should  be  porous  and  loamy  ; 
if  clay,  it  should  be  well  broken  up  and  mixed  with  ashes  ; 
sand  does  not  purify  sewage  well,  especially  at  first,  in 
these  methods.  The  sewage  impurities  are  removed  partly 
by  mechanical  filtration,  but  especially  by  oxidation,  the 

*  Metropolitan  Sewage  Commission  ;  see  Notter  and  Firth,  p.  546. 


IRRIGATION.  413 

latter  being  due  partly  to  tlie  air  in  the  interstices  of  the 
soil,  but  chiefly  to  the  saprophytic  bacteria,  which  rapidly 
convert  the  organic  impurities  into  ammonia,  nitrates, 
nitrites,  and  other  simple  compounds. 

Irrigation  means  "  the  distribution  of  sewage  over  a 
large  surface  of  ordinary  agricultural  ground,  having  in 
view  a  maximum  growth  of  vegetation,  consistently  with 
due  purification,  for  the  amount  of  sewage  supplied."  ^ 
Sub-irrigation  is  a  modification  of  this,  the  se\vage  being 
delivered  through  porous  drains  a  few  inches  beneath  the 
surface  of  the  soil.  Unless  very  porous,  the  laud  should 
be  under-drained  ;  it  should  also  be  levelled  to  prevent  the 
sewage  flowing  off  the  surface  too  rapidly.  The  mider- 
drains  need  not  be  nearly  so  close  together,  however,  as  in 
the  intermittent  filtration  system.  The  crops  raised  on 
irrigation  farms  are  healthful  in  every  respect,  and  there 
can  be  no  reasonable  objection  to  their  use  as  food ;  there 
would  be  decided  objection,  however,  to  sprinkling  the 
vegetables  with  sewage  water. 

For  example,  an  epidemic  of  typhoid  fever  in  Prague 
in  1903  was  traced  to  the  use  of  radishes  which  had  been 
placed  in  polluted  river  water  in  order  to  freshen  them 
and  improve  their  appearance  for  marketing.  It  is  ac- 
cordingly probalile  that  many  cases  of  this  disease  of  ob- 
scure origin  may  arise  in  a  similar  way,  since  it  is  by  no 
means  uncommon  for  the  "  truck  "  o^ardeners  in  the  neisrh- 
borhood  of  cities  to  use  the  contents  of  privy  vaults 
etc.,  as  fertilizer,  and  Rullman  has  shown  that  typhoid 
bacilli  may  live  for  six  months  or  even  a  year  in  human, 
and  more  especially  in  organic,  filth.  Thus  celery,  banked 
for  bleaching  with  such  a  soil,  might  readily  become  a 
carrier  of  the  harmful  germs.     On  the  other  hand,  it  is 

^  Metropolitan  Sewage  Commission  ;  see  Notter  and  Firth,  p.  547. 


414   THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 

hot  likely  that  the  latter  are  carried  to,  and  taken  up  by, 
the  rootlets  of  the  plants  growing  on  the  sewage  farms, 
for  the  records  of  the  latter  thus  far  tend  to  disprove  this. 

On  the  large  irrigation  farms  of  the  city  of  Berlin 
which  has  a  population  of  about  two  million,  the  cost 
of  sewage  disposal  is  about  covered  by  the  returns 
from  the  crops  raised  upon  them.  The  mortality  of 
those  employed  upon  them  is  very  low,  and  there  seems 
to  be  no  particular  tendency  to  illness  that  can  be  at- 
tributed to  the  sewage.  It  is  even  said  that  the  employes 
use  with  impunity  the  clear  water  in  the  effluent  canals 
for  drinking  and  other  purposes.  Paris  has  also  adopted 
the  irrigation  method,  and  hereafter  the  sewage  of  the 
entire  city  will  be  treated  in  this  way.  The  sewage  of 
from  100  to  150  persons  per  acre  may  be  satisfactorily 
disposed  of  by  irrigation,  Berlin's  rate,  with  an  especially 
favorable  soil,  being  142  per  acre.  It  is  to  be  especially 
recommended  for  isolated  houses,  for  small  communities, 
or  for  charitable  or  other  State  institutions. 

The  "  septic  tank  "  system  for  the  disposal  of  sewage 
particularly  aims  to  take  advantage  of  the  biologic  and 
saprophytic  action  occurring  naturally  in  all  polluted 
waters.  The  idea  is  to  favor,  and  not  to  hinder  the  purify- 
ing bacteria  and  other  agencies  by  placing  the  sewage 
under  the  conditions  most  favorable  to  their  growth  and 
action,  thus  facilitating  the  conversion  of  organic  matters, 
both  solid  and  dissolved,  into  substances  entirely  harmless 
and  unobjectionable.  In  other  words,  advantage  is  to  be 
taken  of  the  action  of  both  the  anaerobic  and  aerobic 
.saprophytes  which  abound  in  all  sewage  that  is  not  too 
strongly  impregnated  with  antiseptic  chemical  wastes 
from  factories  or  other  sources.  In  the  intermittent 
filtration  and  irrigation  methods  of   sewage  disposal  the 


THE  SEPTIC  TANK  SYSTEM.  415 

service  of  the  anaerobic  organisms  is  practically  eliminated 
because  the  success  of  these  methods  depends  largely  upon 
a  free  and  frequent  aeration  of  the  filtering  material  or 
the  soil.  On  the  other  hand,  the  purpose  of  the  septic 
tank  is  to  first  make  use  of  the  disintegrating  action  of 
the  anaerobic  bacteria  upon  the  undissolved  organic  matter 
before  subjecting  the  sewage  to  the  action  of  the  aerobic 
bacteria  which  it  contains. 

The  septic  tank  for  large  volumes  of  sewage  should  be 
long  and  comparatively  shallow,  but  should  have  such  a 
capacity  and  cross-section  that  the  sewage  will  pass 
through  at  the  average  rate  of  about  one-half  inch  per 
minute,  and  be  almost,  if  not  quite  twenty -four  hours,  in 
traversing  the  tank.  At  the  upper  end  the  fresh  sewage 
should  enter  within  a  few  inches  of  the  bottom  of  the 
settling  or  '^  grit  chamber,"  which  is  separated  by  a  par- 
tition from  the  rest  of  the  tank,  and  in  which  most  of  the 
street  sand  and  other  inorganic  solids  are  collected. 
Thence  it  goes  into  the  larger  space,  where  the  anaerobic 
bacteria  carry  on  their  work. 

The  tank  may  be  entirely  covered  in  to  exclude  air 
and  light,  for  though  a  thick  scum  or  cake  of  sludge  soon 
forms  on  top  that  would  serve  this  purpose,  there  is  some 
possibility  of  it  being  broken  and  air  admitted  by  ice, 
snow,  and  other  causes.  However,  experience  has  seemed 
to  show  that  some  tanks  without  other  covering  than  the 
sludge  have  seemed  to  work  fairly  well  and  to  give  an 
effluent  as  good  as  that  from  tanks  that  were  covered. 

As  the  sewage  passes  slowly  through  the  long  tank  the 
organic  matter  is  decomposed  with  the  evolution  of  consider- 
able gas  that  may  be  collected  and  used  for  heating  or  light- 
ing purposes,  if  the  tank  and  volume  of  sewage  are  large 
enough  to  warrant  it.    In  a  certain  tank  about  65  feet  long 


416    THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 

through  whicli  the  sewage  flowed  at  a  depth  of  from  7  to 
7|  feet,  and  at  a  daily  rate  of  54,000  gallons  throughout  the 
year,  it  was  found  that  of  the  10  grains  of  mineral  and  14.5 
grains  of  organic  matter  per  gallon  entering  the  tank, 
only  3  grains  of  mineral  and  1.5  grains  of  organic  matter 
per  gallon  remained  in  the  sludge,  the  effluent  being 
quite  clear.  In  other  words,  after  13  or  14  months, 
the  total  solid  residue  exclusive  of  moisture  from  over 
20,000,000  gallons  of  sewage  was  only  5^  tons,  although 
approximately  31^  tons  had  entered  the  tank  in  that  time. 
This  represents  a  reduction  of  more  than  80  per  cent,  of 
the  total  solid  matter.  Moreover,  if  this  amount  of 
sewage  had  been  treated  with  chemicals,  the  sludge  or 
residue  would  have  been  about  45  tons. 

The  outlet  from  the  tank  is  by  a  perforated  or  slotted 
pipe,  located  about  2  feet  below  the  sewage  surface  to 
exclude  light  and  air,  which  may  carry  the  effluent  into  a 
shallow  aerating  trough  over  the  sides  of  which  the  fluid 
flows  in  thin  sheets  and  is  then  led  to  the  aerobic  or  fil- 
tering beds,  every  opportunity  being  given  for  it  to  take 
up  plenty  of  air.  These  beds  are  filled  with  porous 
materials,  such  as  cinders  or  coke,  etc.,  from  -g^  to  |-  inch 
in  size,  the  idea  being  that  there  should  be  as  much 
capacity  for  the  sewage  as  possible,  and  at  the  same  time 
a  ready  aeration  of  the  mass  when  the  bed  is  drained,  the 
beds  becoming  more  efficient  after  being  used  some  time, 
as  they  have  thus  become  impregnated  with  the  right  kinds 
of  bacteria.  After  tilling,  the  beds  are  left  undisturbed  for 
a  c(niple  of  hours,  and  are  then  drained,  after  which  they 
remain  empty  for  ant)ther  two  hours,  it  having  been  found 
possible  by  using  automatic  filling  and  emptying  valves 
to  repeat  the  process  four  times  daily.  It  will  usually  be 
wise  to  carry  the  effluent  from  the  septic  tank  through  at 


FILTRATION  OR  EFFLUENT.  417 

least  two  of  these  beds,  but  if  the  process  is  properly  ac- 
complished, "by  this  purification  an  effluent  is  obtained 
which  is  saturated  with  dissolved  oxygen,  which  remains 
entirely  inoffensive  in  smell  for  an  indefinite  period  in  an 
incubator  at  summer  heat,  and  which  therefore  when  dis- 
charged into  a  M^ater-course  would  maintain  the  respira- 
tion of  fish,  and  would  never  render  the  water  offensive."  ^ 

For  private  suburban  or  country  dwellings,  the  Illinois 
State  Board  of  Health  have  recommended  the  small  septic 
tank  illustrated  in  Figs.  87  and  88,  for  which  the  follow- 
ing description  is  given.^ 

The  plans  show^n  here  are  for  a  tank  suited  to  the  uses 
of  the  ordinary  household  of  from  five  to  ten  persons,  and, 
witii  a  fair  amount  of  intelligent  attention,  it  will  ac- 
complish its  purpose  excellently,  removing  from  the  rural 
or  suburban  home  a  factor  which  is  gradually  becoming 
a  distinct  menace  to  the  public  health. 

This  plant  consists  of  two  tanks,  the  first  the  septic 
tank  proper,  the  second,  a  discharging  tank.  The  septic 
tank  is,  in  construction,  practically  a  cistern  4  feet  in 
diameter  and  about  3  feet  deep.  The  sewage  from  the 
house  enters  this  tank  through  a  lightly  trapped  pipe,  the 
flow  from  the  ordinary  household  preventing  the  back-flow 
of  air.  Across  the  center  of  the  tank  is  a  wall  which 
divides  it  into  two  chambers  of  equal  size.  The  height 
of  this  wall  is  exactly  to  the  point  of  outflow. 

The  sewage  from  the  house  enters  the  first  chamber  of 
the  septic  tank  with  considerable  force,  causing  some  dis- 
turbance of  the  contents.  The  flow  over  the  dividing; 
wall  into  the  second  chamber,  however,  is  even  and  slow, 

1  Leffniann,  "  Civic  Hygiene,"  in  vol.  v.  of  Cohen's  System  of  Physio- 
logic Therapeutics. 

2  See  Bulletin,  vol.  2,  No.  5,  September,  1906. 

27 


418    THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 


Fig.  87. 


Septic  tank  for  private  dwelling. 
Fig.  88. 


FROM  THE  HOUSE 


PLAN 

SCALE  or  FEET 


^5         a         I         5 
Septic  tank  for  private  dwelling. 


SO  that  the  contents  of  tht;  second  cliunibcr  arc  not  disturbed 
and  the  flocculent  matter  settles  readily  to  the  bottom. 
The  bacterial    a(;tion    on  tiie  contents  of  this  tank  is 


FILTRATION  OF  EFFLUENT.  419 

often  so  complete  that  there  is  no  appreciable  residue  or 
sludge,  and  in  this  case  the  tank  will  rarely,  if  ever,  have 
to  be  cleaned  out.  In  some  instances,  however,  the  tank 
will  require  occasional  cleaning.  The  sludge  from  a  well- 
constructed  tank  is  not  ofiensive,  and  may  be  disposed  of 
without  difficulty. 

The  sewage  is  carried  into  the  discharging  chamber 
(which  is  a  cistern  6  feet  in  diameter  and  about  4  feet  in 
depth),  through  a  deeply  trapped  pipe.  The  second  or 
discharging  tank  should  be  of  sufficient  size  to  hold  the 
overflow  from  the  septic  tank  for  a  period  of  12  to  24 
hours.  At  the  bottom  of  the  discharging  tank  is  an  auto- 
matic siphon  which  is  opened  automatically  when  the 
effluent  reaches  a  certain  height  in  the  tank  or  chamber — 
a  height  of  about  2^  feet.  Through  this  siphon  the  con- 
tents of  the  chamber  will  pass  in  a  very  few  moments,  at 
which  time  the  siphon  will  automatically  close  and  the 
chamber  will  again  refill. 

From  the  siphon  a  pipe  conducts  the  effluent,  which  is 
usually  entirely  without  odor  and  is  inoffensive  in  every 
M^ay,  to  the  place  of  discharge,  usually  on  a  lawn,  provided 
it  is  well  under-tiled  and  drained,  or  in  a  pasture  or  field. 

Quoting  also  from  Franklaud,  "  The  recent  experi- 
mental work  on  the  bacterial  treatment  of  sewage  .... 
shows  most  conclusively  that  the  best  results  are  achieved 
by  separating  the  phases  in  which  the  bacterial  purifica- 
tion takes  place,  allotting  distinct  places  to  the  anaerobic 
and  the  aerobic  organisms  respectively  engaged  on  the  work. 

"  The  anaerobic  bacteria  arc  supplied  along  with  the 
sewage,  and  practically  no  difficulty  arises  in  retaining 
ihcir  services  on  the  works  beyond  that  of  providing  them 
with  space  and  time  in  which  to  carry  on  tlieir  labors. 
The  aerobic  bacteria,  however,  demand  air  in  addition  to 


420   THE  REMOVAL  AND  DISPOSAL   OF  SEWAGE. 

space  and  time,  and  if  this  air  be  not  provided  in  sufficient 
quantities  they  go  on  strilce,  and  leave  the  works,  their 
place  being  taken  by  their  less  exacting  anaerobic 
brothers,  who  are,  however,  unable  to  finish  the  work 
of  purification. 

"There  is,  then,  the  constant  tendency  for  the  overflow 
of  the  anaerobic  bacteria  into  the  aerobic  department  of 
the  works,  if  there  be  any  stinting  of  air  in  the  latter. 
In  order  therefore  to  insure  the  services  of  the  aerobic 
bacteria  being  retained  on  the  premises,  it  is  desirable  to 
provide  for  the  aerobic  bacteria  at  least  two  work-shoj)S 
through  which  the  sewage,  on  coming  from  the  anaerobic 
department,  is  made  to  pass. 

"  The  first  of  these  aerobic  work-shops  it  may  be  diffi- 
cult to  provide  with  adequate  ventilation,  the  result  being 
that  both  anaerobic  and  aerobic  bacteria  will  here  be  found 
competing  with  each  other,  and  that  the  aerobic  organisms 
will  be  unable  to  complete  the  work  of  purification. 
The  sewage,  ho^vever,  on  passing  into  the  second  and 
better  ventilated  work-shop  will  there  fall  almost  ex- 
clusively into  the  hands  of  aerobic  bacteria,  which  it  will, 
under  proper  management,  leave  as  an  inodorous,  almost 
pellucid  liquid  incapable  of  putrefaction."  ^ 

Another  writer  summarizes  as  follows:  "As  compared 
with  the  process  of  chemic  precipitation  and  sedimen- 
tation, the  bacterial  process  presents  the  following  advan- 
tages :  (a)  It  requires  no  chemicals.  (6)  It  produces 
no  offensive  sludge,  but  only  a  deposit  of  sand  or  vege- 
table tissue  which  is  free  from  odor,  (c)  It  removes  the 
whole  of  the  suspended  matter,  instead  of  only  about 
80  per  cent,  thereof,  {d)  It  effects  the  removal  of  51.3 
per  cent,  of  the  dissolved  oxidizable  and  putrescible 
1  See  Francis  Wood's  Fracticiil  Sanitary  Engineering,  p.  21G. 


ELECTRICAL   TREATMENT  OF  SEWAGE.        421 

matter,  as  compared  with  tlie  removal  of  only  17  per  cent, 
effected  by  the  present  chemical  treatment,  (e)  The  re- 
sultant liquid  is  entirely  free  from  objectionable  smell,  and 
does  not  become  foul  when  it  is  kept ;  it  further  maintains 
the  life  of  fish."  1 

Electricity  has  also  been  suggested  as  an  agency  for  the 
purification  of  sewage,  but  in  most  localities  is  still  too 
expensive  for  the  purpose.  In  the  Webster  process  iron 
electrodes  are  used,  and  the  favorable  results  are  supposed 
to  be  due  partly  to  the  hypochlorites  which  are  formed 
from  the  chlorides  always  present  in  the  sewage,  and  partly 
to  the  carbonates  and  oxides  of  iron,  which  not  only  de- 
odorize but  also  help  to  oxidize  rapidly  the  organic  matters. 
By  this  method  about  70  per  cent,  of  the  putrescible  mat- 
ters and  almost  all  the  bacteria  are  removed  from  the 
sewage,  but  it  is  still  rather  costly  on  account  of  the  large 
amount  of  iron  consumed. 

The  selection  of  the  method  of  sewage  disposal  has  in 
tlie  past  been  made  too  hastily  or  without  sufficient  con- 
sideration by  some  communities,  with  correspondingly  un- 
satisfactory results.  In  all  cases,  careful  and  scientific 
tests,  covering  the  several  seasons  of  the  year,  and  taking 
into  consideration  local  conditions  and  factors,  should  be 
made  riot  only  of  various  methods,  but  of  different  com- 
binations of  methods,  sufficient  time  being  taken  to  deter- 
mine the  value  of  each.  A  decision  arrived  at  in  this 
way  will  be  most  likely  to  prove  satisfactory  and  to  be  the 
most  economical  and  salutary  to  all  concerned. 

1  American  Year-book  of  Medicine  for  1900,  p.  549. 


CHAPTEK    XIII. 

MILITAEY  HYGIENE. 

This  subject  is  one  which  has  to  do  with  active  and 
presumably  healthy  men  under  conditions  more  or  less 
abnormal  and  sometimes  of  a  peculiar  and  unusual  stress. 
Moreover,  the  actual  financial  value  of  the  life  and  health 
of  the  individual  to  the  State  is  more  directlj  manifest 
than  under  ordinary  circumstances,  and,  though  at  times 
the  interests  of  the  former  must  be  sacrificed  to  those  of 
the  latter,  it  is  of  the  highest  economic  and  practical  im- 
portance that  a  government  should  conserve  as  far  as 
possible  the  health  and  welfare  of  each  member  of  its 
army  and  navy.  Consequently,  much  thought  should  be 
and  is  given  to  all  those  questions  which  rightly  come 
under  this  head,  and  the  effect  of  the  efforts  made  in  this 
direction  is  very  decided,  especially  with  reference  to  the 
regular  or  standing  armed  force  of  the  country. 

Men  who  have  become  accustomed  to  military  service, 
and  to  whom  it  is  a  real  and  permanent  business,,  have 
probably  a  better  health  status  than  the  average  citizen, 
owing  to  the  regularity  of  their  habits  and  work  and  to 
tlie  oversight  and  care  which  are  given  to  the  details  of 
their  life.  Conditions  are  much  different,  however,  when 
men  are  suddenly  called  from  many  occupations  and  ways 
of  living  to  volunteer  or  militia  service.  They  do  not 
accommodate  themselves  readily  to  tlie  change,  nor  do 
they  appreciate  the  importance  of  details  that  may  seem 

422 


EXAMINATION  AND  SELECTION  OF  RECRUITS.  423 

trivial  to  them  but  that  have  great  bearing  on  their  future 
health.  Often  the  utmost  efforts  on  the  part  of  those  in 
authority  and  who  are  skilled  in  these  matters  are  appar- 
ently of  no  avail  and  lead  to  undeserved  censure.  How 
much  more  serious  actual  neglect  of  hygienic  measures 
may  be  has  been  proved  more  than  once  in  the  past. 

The  following  quotation  from  the  Report  of  the  Sur- 
geon-General of  the  Army  for  1899  is  pertinent : 

"  Hygiene  is  one  of  the  principal  subjects  of  examina- 
tion for  candidates  desiring  appointment  in  the  medical 
corps  of  the  army,  and  at  the  subsequent  examinations  for 
promotions  to  the  grades  of  captain  and  major  it  is  given 
a  most  prominent  place.  It  is  also  the  most  prominent 
subject  in  the  course  of  instruction  at  the  Army  Medical 
School,  where  the  student  officers  spend  five  hours  daily 
for  a  period  of  five  months  in  practical  laboratory  work 
relating  for  the  most  part  to  the  cause  and  prevention  of 
infectious  diseases;  but  the  comparatively  small  number 
of  medical  officers  of  the  regular  army  available  for  duty 
in  the  large  camps  occupied  by  our  volunteer  troops  at 
the  outset  of  the  war  (Spanish- American)  proved  to  be 
entirely  inadequate  to  control  the  sanitary  situation  in 
these  camps." 

In  a  study  of  military  hygiene,  all  phases  of  the  routine 
life  of  the  soldier  should  be  discussed,  for  it  is  the  combin- 
ation of  these  that  make  for  good  or  evil. 

Unless  the  emergency  is  grave  and  large  numbers  of 
men  are  needed  quickly,  much  attention  should  be  paid 
to  the  selection  of  the  men,  and  only  those  enlisted  who 
satisfy  certain  physical  requirements.  They  should  be 
neither  abnormally  short  nor  tall ;  the  weight  should  be 
in  proper  ratio  to  the  height ;  the  vision  and  general  health 
good,  and  especially  should  the  chest  measurement  and 


424  MILITARY  HYGIENE. 

expansion  or  "  vital  capacity  "  be  considered  as  of  great 
importance. 

"  It  has  also  been  observed  that  a  close  correlation 
exists  between  the  physical  and  moral  development  of 
men ;  in  fact,  lowering  the  physical  means  lowering  the 
moral  standard  of  recruits."^ 

Age  is  also  a  factor  that  should  be  considered.  If 
recruits  are  too  young,  they  are  not  able  to  withstand 
long-continued  work  or  strain,  nor  will  they  be  so  likely 
to  resist  the  incurrence  of  disease.  On  the  other  hand, 
men  who  are  too  old  will  be  more  liable  to  have  habits  of 
life  or  taints  of  chronic  disease  that  will  interfere  with 
their  military  duty,  and  they  will  also  not  serve  the 
maximum  length  of  time  that  makes  their  work  most 
economical  to  the  government. 

"  The  medical  officer's  first  duty  is  rigorously  to  examine 
his  command,  if  it  has  been  newly  raised,  and  inexorably 
to  eliminate  all  men  unfit  for  full  military  duty.  Upon 
the  medical  officer  who  examines  recruits  for  enlistment 
lies  a  heavy  responsibility,  for  it  practically  rests  witli 
him  to  determine  the  physical  efficiency  of  the  command. 
Unfortunately  in  time  of  war,  when  the  necessity  for 
effective  men  is  the  greatest,  this  selection  is  apt  to  be 
devolved  upon  untrained  civilians  who  have  neither  the 
special  knowledge  that  fits  them  as  judges  nor  the  position 
tliat  enables  them  in  doubtful  cases  to  withstand  the  con- 
stant importunities  of  still  less  informed  recruiting  officers. 
The  careful  examination  of  recruits  is  not  practical  hygiene, 
but  the  successful  application  of  liygione  requires  carefully 
selected  men  to  secure  the  best  results."  ^ 

'  Xottcr  and  Firth,  p.  917. 

''Colonel  A.  A.  Woodhnll,  article  on  "Military  Hygiene"  in  Eefer- 
ence  Handbook  of  the  Medical  Sciences. 


LOCATION   OF  CAMPS.  425 

In  selecting  the  sites  for  camps  or  homes  of  soldiers, 
consideration  must  be  had  as  to  -whether  these  are  to  be 
temporary  or  permanent,  and  as  to  whether  tlie  men  are 
to  live  in  tents  or  barracks.  In  any  case,  there  should  be 
sufficient  space  allotted  to  each  command;  there  should  be 
no  interference  with  the  free  circulation  of  air,  and  the 
soil  should  be  dry,  porous,  and  readily  drained.  The 
ground- water  especially  should  not  be  too  near  the  sur- 
face. Camps  should  not  be  located,  except  in  event  of 
grave  military  necessity,  on  ground  that  has  been  recently 
occupied  by  other  troops ;  nor  should  they  be  on  clay 
soils,  in  ravines  or  valleys  where  they  will  receive  the 
drainage  from  higher  ground  or  other  camps,  nor  near 
marshes  or  the  marshy  banks  of  rivers,  nor  where  they 
will  receive  the  winds  from  malarial  districts.  Thought 
should  also  be  given  to  the  source  and  abundance  of  the 
water-supply  and  its  relation  to  the  natural  course  of 
drainage  from  the  camp. 

If  tents  are  to  be  used,  these  must  be  such  as  to  afford 
both  thorough  protection  and  good  ventilation.  They 
should  not  be  too  crowded,  either  as  regards  the  number 
of  occupants  in  each  or  the  location  of  the  tents  one  to 
another.  If  the  camp  is  of  extended  duration,  the  tents 
should  be  floored,  or  at  least  the  men  should  not  sleep  on 
the  ground. 

A  trench  slinuld  also  be  dug  about  each  tent  to  prevent 
flooding  by  rains,  and  from  time  to  time  the  tents  should 
be  moved  about,  as  "  it  is  well  known  that  tents  occupy- 
ing the  same  ground  for  a  length  of  time  become  un- 
healthy." Camp  kitchens,  stables,  sinks,  latrines,  etc., 
should  be  as  far  from  the  sleeping  tents  as  reasonable 
convenience  permits,  and  to  the  leeward  of  prevailing 
winds.      All    camps    should  be    regularly    and    carefully 


426  MILITARY  HYGIENE. 

policed,  and  "  the  fact  that  a  camp  expects  to  change  its 
position  does  not  justify  neglect  of  proper  policing  of  the 
ground  occupied." 

In  the  regulations  and  instructions  issued  in  1895  by 
the  British  Quartermaster-General's  Department  the  fol- 
lowing points  are  laid  down  as  of  importance  : 

"  1.  The  length  of  time  troops  are  to  occupy  the  camp- 
ing-ground. 2.  That  order,  cleanliness,  ventilation,  and 
salubrity  are  to  be  insured.  3.  That  means  of  passing 
freely  through  the  camp  are  essential.  4.  That  a  strag- 
gling camp  increases  labor  of  fatigue  duties,  and  impedes 
delivery  of  supplies  and  circulation  of  orders.  5.  That 
the  more  compact  the  camp,  the  easier  it  is  to  defend."' 

If  the  soldiers  are  assigned  to  forts  or  other  permanent 
encampments,  they  will  probably  be  quartered  in  barracks, 
and  these  A\"ill  have  been  constructed  according  to  specifi- 
cations. However,  it  should  be  remembered  that  in  these 
attention  must  be  given  not  only  to  the  comfort  of  the 
men,  but  to  their  sanitary  needs  as  well,  and  that  the 
chief  faults  in  such  structures  in  the  past  have  been  insuffi- 
cient ventilation  and  improper  location  and  arrangement 
of  toilet-rooms,  etc. 

Barrack  buildino^s  should  not  be  more  than  two  stories 
in  liciirht,  slionld  l)e  comparatively  narrow,  should  have 
free  ventilation  and  access  of  sunlight  about  them,  and 
shouhl  be  so  placed  that  they  do  not  interfere  with  one  an- 
otlier  in  tliese  res]^ects.  It  will  Ijo  well  if  each  sleejiing- 
room  is])lann('d  to  eontain  not  more  than  t\v(^nty-fivc  men 
or  a  quarter  company.  Each  man  should  liave  at  least 
000  cubic  feet  f)f  air-space  in  his  dormitory  ;  with  ceilings 
twelve  feet  higli,  this  will  give  him  fifty  square  feet  of 
floor-space.  Toilet-rooms  should  be  separated  from  the 
1  Notter  and  Firth,  p.  930. 


BUILDINGS   OF  PERMANENT  ENCAMPMENTS.  427 

dormitories  by  a  continually  ventilated  passage-way,  at 
least ;  it  would  be  better  to  have  the  'former  entirely  apart 
from  the  latter. 

Kitchens,  dining-  or  mess-rooms,  guard-rooms,  and 
quarters  for  married  men  should  be  in  separate  build- 
ings and  apart  from  the  barracks,  and  these  should  each 
be  properly  arranged  for  its  purpose.  The  same  remarks 
apply  to  the  post-hospital,  which  should  have  as  complete 
an  equipment  as  possible  in  accordance  with  the  demands 
of  modern  medical  and  surgical  science ;  and  conse- 
quently, in  addition  to  the  general  wards,  there  should  be 
others  for  the  isolation  of  contagious  or  infectious  cases 
and  for  the  insane.  It  goes  without  saying  that  the 
officers'  quarters  should  have  every  hygienic  and  sanitary 
advantage  and  convenience,  both  as  to  construction  and 
location,  that  the  circumstances  of  the  post  will  permit. 

In  such  permanent  encampments,  where  the  accommo- 
dations and  conveniences  more  nearly  resemble  those  in 
the  home  of  the  average  private  citizen,  and  where  proper 
food,  an  ample  supply  of  unpolluted  water,  and  suitable 
arrangements  for  the  removal  of  wastes  and  sewage  can 
all  be  provided  for,  it  will  ordinarily  not  be  difficult  for 
the  well-informed  medical  officer  to  maintain  a  satisfactory 
sanitary  condition,  and,  owing  to  the  discipline  and  super- 
vision of  their  habits  to  which  the  men  are  subjected,  as 
well  as  to  the  fact  that  they  are  adults  and  males,  the 
general  health  status  of  the  post  should  usually  be  better 
than  the  average  of  the  neighboring  communities. 

But  conditions  and  circumstances  are  much  different  on 
the  "tented  field,"  and  especially  so  if  the  command 
belong  to  the  militia  or  volunteer  service,  in  which  the 
men  have  been  called  from  many  and  various  occupations, 
are  unaccustomed  to  the  hardships  of  military  life  and 


428  MILITARY  HYGIENE. 

the  vicissitudes  of  out-door  living,  and  are  unmindful — 
as  they  will  be  at  first — of  the  restraints  and  value  of  dis- 
cipline. Even  though  the  medical  officers  be  well  versed 
in  hygienic  knowledge  and  thoroughly  aware  of  the  im- 
portance of  the  strict  observance  of  sanitary  precautions, 
and  though  they  have  the  hearty  assistance  of  the  com- 
manding officers,  it  will  take  much  time  so  to  instruct  the 
men  that  they  will  not  endanger  the  health  of  themselves 
and  others,  and  eternal  vigilance  and  much  effijrt  will  be 
the  price  of  a  continuously  satisfactory  state  of  affairs. 

"  In  time  of  war  there  is  added  a  new  army  of  volun- 
teers, whose  men  are  often  accepted  without  proper  scru- 
tiny. The  preservation  of  these  men  from  disease  is  the 
chief  concern  of  the  medical  officer,  miscalled  the  sur- 
geon."^ 

The  recent  experience  of  this  country  in  the  Spanish- 
American  War  is  vivid  in  the  minds  of  every  one,  espe- 
cially as  regards  the  sanitary  conditions  and  the  epidemic 
sickness  in  practically  all  the  camps  throughout  the  coun- 
try. And  while  there  was  much  that  was  censurable, 
there  was  still  much  unjust  censure  given  by  those  who 
did  not  understand  to  those  who  did  and  who  strove  to 
the  utmost  to  overcome  the  untoward  and  unfortunate 
conditions. 

In  August,  1898,  a  board  of  medical  officers  was  ap- 
pointed by  the  Surgeon-General  of  the  United  States 
Army  to  "ascertain  the  causes  of  the  existence  and  spread 
of  typhoid  fever  in  the  national  encampments,  and  to 
suggest  means  of  its  abatement."  The  results  of  their 
work,  as  epitomized  by  one  of  them.  Prof.  ■  Victor 
C.  Vaughan,  in  his  "  Oration  on  State  Medicine "  be- 
fore the  annual  meeting  (1900)  of  the  American  Medical 

1  Colonel  Woodhull,  loc.  cit. 


TYPHOID  FEVER  IN  CAMPS.  429 

Association/  are  very  instructive  and  are  worth  quoting 
almost  entire  : 

"Every  regiment  in  the  United  States  service  in  1898 
developed  typhoid  fever.  Typhoid  fever  not  only  ap- 
peared in  every  regiment  in  the  service,  but  it  became 
epidemic,  both  in  the  small  encampments  of  not  more  than 
one  regiment,  and  in  the  larger  ones  consisting  of  one  or 
more  corps.  Typhoid  fever  became  epidemic  in  camps 
located  in  the  Northern  as  well  as  those  in  the  Southern 
States ;  and  it  is  so  widely  distributed  in  this  country  that 
one  or  more  cases  are  likely  to  appear  in  any  regiment 
within  eight  weeks  after  assembly.  Typhoid  fever  usually 
appears  in  military  expeditions  within  eight  weeks  after 
assembly. 

"With  typhoid  fever  as  widely  disseminated  as  it  is  in 
this  country,  the  chances  are  that  if  a  regiment  of  1300 
men  should  be  assembled  in  any  section  and  kept  in  a 
camp  the  sanitary  conditions  of  which  were  perfect,  one 
or  more  cases  of  typhoid  fever  would  develop. 

"  Neither  the  miasmatic  theory  nor  the  pythogenic 
theory  of  the  origin  of  typhoid  fever  is  supported  by  the 
investigations,  but  they  confirm  the  doctrine  of  the  specific 
origin  of  typhoid  fever.  It  is  disseminated  by  the  trans- 
ference of  the  excretions  of  an  infected  individual  to  the 
alimentary  canals  of  others,  and  it  is  more  likely  to  be- 
come epidemic  in  camps  than  in  civil  life,  because  of  the 
greater  difficulty  of  disposing  of  the  excretions  from  the 
human  body.  A  man  infected  with  typhoid  fever  may 
scatter  the  infection  in  every  latrine  of  a  regiment  before 
the  disease  is  recognized  in  himself. 

"  Camp  pollution  was  the  greatest  sanitary  sin  com- 
mitted by  the  troops  in   1898,  and  it  may  be  stated  in  a 

^  See  Journal  of  American  Medical  Association^  June  9,  1900. 


430  MILITARY  HYGIENE. 

general  way  that  the  number  of  cases  of  typhoid  fever  in 
the  cl liferent  camps  varied  with  the  method  of  disposing 
of  excretions.  Tlie  tub  system  of  disposal  of  fecal  matter 
as  practised  in  certain  divisions  is  to  be  condemned,  and 
the  regulation  pit  system  is  not  a  satisfactory  system  of  • 
disposing  of  fecal  matter  in  permanent  camps.  The 
Board  has  recommended  that  in  permanent  camps  where 
water-carriage  cannot  be  secured,  all  fecal  matter  should 
be  disinfected  and  then  carted  away  from  camp. 

"  Some  commands  were  unwisely  located,  and  in  some 
instances  the  space  allotted  the  regiments  was  inadequate. 
Many  commands  were  allowed  to  remain  on  one  site  too 
long,  and  requests  for  change  in  location  made  by  medical 
officers  were  not  always  granted.  Greater  authority 
should  be  given  medical  officers  in  matters  relating  to  the 
hygiene  of  camps.  Superior  line  officers  cannot  be  held 
altogether  blameless  for  the  insanitary  condition  of  the 
camps. 

•'  Infected  water  was  not  an  important  factor  in  the 
spread  of  typhoid  fever  in  the  national  encampments  in 
1898.  Flies  undoubtedly  served  as  carriers  of  the  infec- 
tion ;  it  is  prol)al)le  that  the  infection  was  disseminated  to 
some  extent  through  air  in  the  form  of  dust ;  personal 
contact  was  undoubtedly  one  of  the  means  by  which  it  was 
spread,  and  it  is  more  than  likely  that  men  transported 
infected  material  on  their  persons  and  clothing,  and  thus 
disseminated  the  disease. 

"A  command  badly  infected  with  typhoid  fever  does 
not  lose  the  infection  by  simply  changing  location,  but 
when  it  changes  its  location  it  carries  the  specific  agents 
of  the  disease  in  the  bodies  of  tlie  men,  in  their  clothing, 
bedding,  and  tontage,  and  even  an  ocean  voyage  does  not 
relieve  an  infected  command  of  its  infection.     However, 


TYPHOID  FEVER  IN  CAMPS.  431 

after  a  command  becomes  badly  infected  with  typhoid, 
change  of  location,  together  with  thorough  disinfection  of 
clothing,  bedding,  and  tentage,  is  necessary. 

"  Except  in  case  of  most  urgent  military  necessity,  one 
command  should  not  be  located  on  a  site  recently  vacated 
by  another,  but  the  fact  that  a  command  expects  to  change 
its  location  does  not  justify  neglect  of  proper  policing  of 
the  ground  occupied. 

"  It  is  desirable  that  soldiers'  beds  should  be  raised 
from  the  ground,  and  medical  officers  should  insist  that 
soldiers  remove  their  outer  clothing  at  night  when  the 
exigencies  of  the  situation  permit.  In  some  of  the 
encampments  the  tents  were  too  nmch  crowded. 

"  ^lalaria  was  not  a  prevalent  disease  among  the  troops 
that  remained  in  the  United  States,  and  while  the  inves- 
tigations show  that  coincident  infection  with  malaria  and 
typhoid  fever  may  occur,  the  resulting  complex  of  symp- 
toms does  not  seem  to  be  sufficiently  well  defined  and 
uniform  to  be  recognized  as  a  separate  disease.  The 
continued  fever  that  prevailed  among  the  soldiers  in  this 
countrs'  in  1898  was  typhoid  fever,  but  in  military  prac- 
tice typhoid  is  often  apparently  an  intermittent  disease. 

"About  one-fifth  of  the  soldiers  in  the  national  encamp- 
ments in  the  United  States  in  1898  developed  typhoid 
fever ;  army  surgeons  correctly  diagnosed  a  little  less  than 
one-half  the  cases  of  typhoid  fever,  and  while  the  deaths 
from  typhoid  fever  were  more  than  80  per  cent,  of  the 
total  deaths,  the  percentage  of  deaths  among  cases  of 
typhoid  fever  was  about  7.5.  When  a  command  is  thor- 
oughly saturated  with  typhoid  it  is  probable  that  from 
one-third  to  one-quarter  of  the  men  will  be  found  suscep- 
tible to  the  disease. 

"  The  belief  that  errors  in  diet,  with  consequent  gastric 


432  MILITARY  HYGIENE. 

and  intestinal  catarrh,  induced  typhoid  fever,  or  that 
simple  gastro-intestinal  disturbances  predispose  to  it,  is 
not  supported  by  the  investigations.  More  than  80  per 
cent,  of  the  men  who  developed  typhoid  fever  had  no 
preceding  intestinal  disorder. 

"  The  shortest  period  of  incubation  in  typhoid  fever  is 
probably  something  under  eight  days,  and  one  who  has 
lived  in  a  camp  in  which  typhoid  fever  is  prevalent  is 
liable  to  develop  this  disease  any  time  within  eight  weeks 
after  leaving  such  a  camp." 

In  great  contrast  with  this  experience  and  that  of  other 
great  nations  was  the  record  of  the  Japanese  army  in  the 
recent  Russo-Japanese  war.  In  spite  of  great  privations, 
almost  incredible  exertions,  and  other  factors  that  favored 
the  development  of  typhoid  fever  and  other  infectious  dis- 
eases in  epidemic  form,  this  army  remained  almost  entirely 
free  from  their  incidence,  and  the  death-rate  attributable 
to  them  was  so  far  below  that  of  any  previous  experience 
of  similar  nature  as  to  excite  the  surprise  and  admiration 
of  the  professional  world.  And  yet  the  result  was  obtained 
simply  by  making  the  medical  officers  of  the  Japanese  forces 
supreme  in  authority  in  all  matters  pertaining  to  the  health 
of  the  troops  under  their  command,  and  by  the  practical  ob- 
servance and  carrying  out  of  sanitary  principles  already  well 
known  in  their  entirety  by  every  physician  of  intelligence. 
It  is,  therefore,  to  be  hoped  that  hereafter  the  medical 
officers  of  the  military  and  naval  forces  of  the  so-called 
civilized  nations  may  be  granted  more  power  and  authority 
than  they  have  been  able  to  obtain  in  the  past. 

So  much  has  been  included  in  the  above  quotations, 
looking  in  so  many  different  directions,  that  it  would 
seem  that  there  were  little  more  to  say  on  the  subject. 
However,  a  few  words  must  be  added. 


THE  FOOD   OF  THE  SOLDIER.  433 

Despite  the  fact  that  malaria  was  apparently  not  very 
prevalent  among  the  troops  in  this  country  in  the  late 
war,  it  is  a  disease  that  is  often  very  harmful  and  disas- 
trous to  armies.  So  is  dysentery  and,  in  other  climates 
or  countries,  yellow  fever  and  cholera.  On  account  of 
the  recent  discoveries  regarding  the  influence  of  the  mos- 
quito in  transporting  the  germs  of  malaria,  yellow  fever, 
and  other  diseases,  a  simple  mosquito  bar  or  net  should 
be  included  in  the  kit  of  every  soldier,  and  the  Sur- 
geon-General's report  of  1899  seems  to  give  evidence 
of  its  efficacy  in  preventing  such  diseases  among  our 
soldiers  in  Cuba.  As  dysentery  and  cholera  are  well 
known  to  be  transmitted  by  drinking-water,  sanitary 
precautions  as  to  the  care  of  the  water  must  be  ob- 
served. Though  the  quotation  above  states  that  "in- 
fected water  was  not  an  important  factor  in  the  spread 
of  typhoid  fever,  etc.,"  it  must  not  be  inferred  that 
no  cases  were  found  to  be  due  to  such  water.  In  fact, 
many  cases  were  undoubtedly  thus  caused  as  Vaughan 
clearly  states ;  but  the  authorities,  early  realizing  the 
dangers  that  might  be  due  to  a  bad  water,  made  such 
efforts  to  obtain  pure  supplies  that  other  means  of  in- 
fection became  relatively  more  important.  Every  effort 
sliould  therefore  be  made  to  secure  the  purest  water-supply 
possible  in  every  military  camp,  and  to  have  it  thoroughly 
sterilized  before  use  if  there  is  any  suspicion  of  its  pollu- 
tion. A  full  description  of  filtration  methods  and  of  the 
sterilizer  that  has  been  adopted  by  the  army  has  been 
given  in  the  chapter  on  Water. 

As  the  efficiency  of  the  soldier  depends  so  much  upon 

his  food,  and  as  it  is  of  importance  for  so  many  diflerent 

reasons,  it  is  not  strange  that  it  has  been  the  subject  of 

the   most  careful    investigation.      In   fact,   much   of  the 

28 


434  MTLTTART  HYGIENE. 

scientific  knowledge  now  pertaining  to  dietetics  is  the 
result  of  the  work  of  the  various  governments  in  their 
efforts  to  determine  the  most  satisfactory  and  efficient 
military  rations.  Considering  the  men  simply  as  ma- 
chines, true  economy  requires  that  their  food  shall  be 
ample  in  quantity  and  good  in  quality.  Attention  must 
also  be  given  to  its  transportation  and  preparation,  and  to 
its  character  as  a  source  of  heat  and  energy. 

A  study  of  the  standard  daily  rations  of  the  various 
armies  of  the  world  at  once  shows  a  noticeable  uniformity 
among  them  in  the  amounts  and  relative  proportion  of 
the  food-principles  and  in  the  ratio  of  nitrogen  and  carbon. 
And  as  these  have  all  had  the  test  of  long  time  and  exten- 
sive experience,  they  serve  to  establish  their  own  scientific 
accuracy,  as  well  as  that  of  the  dietetic  ratios  M'hich 
have  been  determined  in  other  ways  and  to  which  they 
so  closely  correspond. 

No  part  of  a  military  administration  is  of  more  im- 
portance than  the  commissary  department,  for  an  army 
without  food  is  soon  worse  than  useless.  But  it  is  not  easy 
to  feed  properly  large  numbers  of  men  in  an  active  cam- 
paign when  the  whole  body  is  moving  rapidly  from  place 
to  place  and  when  the  exigencies  of  the  day  may  seem  to 
require  all  available  means  of  trausportation  for  other 
purposes.  Consequently,  much  effort  has  been  made  to 
supply  rations  that  are  condensed  in  bulk  and  that  require 
as  little  immediate  pre^jaration  as  possible. 

Considerable  advance  in  this  line  has  been  made  in 
recent  years,  and  various  souj)s,  meats,  and  vegetables, 
condensed  and  ready-cijoked,  are  now  often  siqqjlied  when 
the  same  cannot  be  had  in  a  fresh  state.  That  such  may 
be  entirely  satisfactory  cannot  be  denied,  but  those  in 
authority  must  be  especially  careful  as  to  certain  points, 


THE  CLOTHING   OF  THE  SOLDIER.  435 

viz.,  that  the  food  is  not  lacking  in  quality  and  that  the 
processes  employed  have  not  impaired  its  dietetic  value  or 
digestibility  nor  permitted  harmful  changes  to  take  place 
in  it.  The  temptations  of  the  army  contractor  are  often 
hard  to  withstand ;  moreover,  tests  have  shown  that  if 
concentration  be  carried  too  ftir,  not  only  the  digestibility, 
Init  the  nutritive  value  as  well  of  the  food  may  be  seriously 
impaired.  Thus  the  A'aluable  salts  may  be  lost  with  the 
water  in  the  compression  of  vegetables.  Again,  the  proc- 
esses may  make  the  foods  too  uniform  in  taste,  or  there 
may  be  the  omission  of  such  accessories  as  vinegar,  spices, 
etc.,  or  there  may  be  ignorance  as  to  how  to  cook  them 
properly  ;  and  it  must  always  be  remembered  tliat  pala- 
tability  has  much  to  do  Avith  digestibility.  For  these 
reasons  it  will  be  wise  to  have  at  least  part  of  the  food 
issued  in  as  nearly  the  fresh  or  ordinary  state  as  possible. 

Space  does  not  permit  consideration  of  the  various 
articles  of  food  composing  the  prescribed  ration,  but  it  is 
evident  that  the  laws  of  dietetics  govern  here  as  elsewhere. 
It  may  be  well  to  say,  however,  that  experience  seems  to 
show  that  alcohol  should  not  be  included  in  the  regular 
ration,  but  should  only  be  issued,  if  at  all,  in  certain 
exigencies  and  in  small  quantities. 

Tlie  same  principles  hold  good  in  regard  to  soldiers' 
clothing  as  for  that  of  other  people,  but  "  in  selecting  the 
material  the  chief  points  to  be  considered  are  its  permea- 
bility, durability,  and  the  property  it  has  of  conducting 
and  absorbing  lieat."  It  would  be  well  if  the  undergar- 
ments were  always  in  part,  at  least,  of  wool.  The  mate- 
rial of  the  uniforms  and  its  weight  should  depend  upon 
tlie  exigencies  of  the  service,  considering  both  the  locality 
and  the  season  of  the  year.  In  cold  weather  wool  sliould, 
of  course,  have  first  place;  in  liot  climates  the  stout  cottcm 


436  MILITARY  HYGIENE. 

fabric  called  khaki  seems  to  meet  the  conditions  most  satis- 
factorily. "  The  color  of  the  material  has  an  important 
bearing  on  the  hygienic  value  of  the  clothing,  and  in 
regard  to  the  absorption  of  heat  exerts  more  influence 
than  the  material  itself.  .  .  .  \Yhite  possesses  very  slight 
absorptive  power  compared  to  other  colors,  and,  next  to 
this  in  the  scale,  gray  or  pale  yellow  gives  the  best  results. 
Gray  is  the  best  color  for  soldiers'  dress  on  service,  for 
white  is  least  suited  to  the  field,  as  it  soils  so  quicklv. 
The  khaki  drill  corresponds  very  closely  with  gray  as 
regards  absorption  power."  ^ 

The  clothing  should  nowhere  be  so  tight  as  to  interfere 
with  respiration  or  circulation  or  with  free  movement  of 
the  body.  There  should  be  a  sufficiency  of  socks  in  each 
man's  kit,  for  "a  good  sock  kept  clean,  is  a  protective 
against  sore  feet."  Boots  or  shoes  should  l^e  comfortable 
as  ^vell  as  durable  and  waterproof.  Leggings  may  often 
be  used  to  advantage  ;  they  may  be  of  stout  canvas,  khaki, 
or  leather.  Helmets  or  other  head-dress  should  be  light 
and  well  ventilated,  and  of  a  non-absorbent  color.  Ab- 
dominal bands  of  flannel  are  excellent  protectives  against 
digestive  disturbances,  if  the  men  can  be  induced  to  wear 
them.  Each  kit  should  contain  a  rubber  or  waterj^roof 
blanket  to  protect  the  soldier  from  the  dampness  of  the 
ground  at  night  ;  it  can  also  be  used  as  a  cape  in  rainy 
weather.  The  weight  of  the  kit,  arms,  accoutrement,  etc., 
is  often  excessive,  and  should  be  kept  as  light  as  possible. 
In  some  armies  as  much  as  seventy  pounds  is  to  be  car- 
ried by  each  soldier.  It  should  be  so  divided  that,  when 
on  the  march,  as  much  of  this  as  possible  can  and  should 
be  carried  in  wagons  for  the  men,  they  retaining  only 
their  arms  and  water  bottles.  "  "Weights  are  most  easily 
'  Notter  and  Firth,  p.  955. 


DISPOSAL   OF  CAMP   WASTES.  437 

borne  when  the  following  points  are  attended  to:  1.  They 
must  be  as  near  the  centre  of  gravity  as  possible.  2.  The 
weights  must  in  no  case  compress  the  lungs,  or  interfere 
with  the  respiratory  movements  or  the  elimination  of  car- 
bon dioxide,  or  hinder  the  transmission  of  blood  through 
the  lungs,  or  render  difficult  the  action  of  the  heart. 
3.  ]\^o  important  muscles,  vessels,  or  nerves  should  be 
pressed  upon.  4.  The  weights  should  be  distributed  as 
much  as  possible  over  several  parts  of  the  body."  ^ 

The  last  statement  means  that  the  pressure  will  be  most 
advantageously  put  upon  the  tops  of  the  shoulder-blades 
and  upon  the  hip-bones  and  sacrum. 

The  disposal  of  the  wastes  of  a  camp  constitutes  one  of 
its  gravest  problems.  If  it  is  a  permanent  post  and  the 
men  are  quartered  in  barracks  with  a  sufficient  water- 
supply,  it  may  be  best  to  construct  a  complete  sewerage 
system ;  but  where  the  encampment  is  temporary  the  dif- 
ficulties are  greatly  increased.  Even  though  the  camp  is 
strictly  policed,  as  it  always  should  be,  and  the  garbage 
and  similar  wastes  destroyed  by  fire  or  burial,  there  re- 
mains the  disposal  of  the  excreta  of  large  numbers  of  men, 
which,  if  neglected,  is  almost  certain  to  become  a  source 
of  infection. 

The  customary  sinks  are  not  only  liable  to  pollute  the 
ground-water  and  perhaps  the  water-supply  of  the  camp, 
but  they  are  also  a  constant  offence  to  the  senses,  and  we 
now  know  that  infection  may  be  carried  by  flies  directly 
from  them  to  the  food  in  the  kitchens  and  mess-tents. 
Where  used,  their  contents  should  be  covered  thrice  daily 
with  a  layer  of  fresh  earth  or  lime,  and  when  the  contents 
reach  within  two  feet  of  the  surface  they  should  be  filled 
with  earth   and   new  ones  opened.     A  medical  officer  has 

1  Notter  and  Firtb,  pp.  961,  962. 


438  MILITARY  HYGIENE. 

recently  suggested  that  instead  of  using  earth  or  lime  for 
a  covering,  dry  grass  or  straw  be  sj^read  over  the  con- 
tents and  burned  two  or  three  times  a  day.  This  would 
not  only  serve  to  disinfect  the  surface  and  sides  of  the 
trench  by  fire,  but  the  ashes  of  the  straw  would  form 
a  loose  covering  of  several  inches'  thickness  which  would 
completely  conceal  the  sul^sequent  additions  and  at  the 
same  time  effectually  protect  all  the  contents  from  the 
access  of  flies.  Colonel  Woodhull  suo^gests  the  burning: 
twice  a  day  of  small  quantities  of  petroleum  poured  on  the 
surface  of  the  contents  of  the  sink. 

However,  it  will  be  wiser  to  do  away  with  sinks 
altogether  and  to  jirovide  measures  whereby  the  excreta 
can  be  at  once  chemically  disinfected  and  then  removed 
beyond  the  limits  of  the  camp.  Theoretically,  the  tub  or 
pail  system  would  seem  to  be  available  if  proper  dis- 
cipline and  supervision  could  be  had  ;  but  the  recent 
experience  in  certain  camps  rather  proves  it  to  be  unsatis- 
factory. Unless  the  contents  are  disinfected  immediately, 
the  soil  about  the  camp  Avill  be  almost  certainly  polluted 
and  infected  when  the  receptacles  are  removed  for  empty- 
ing, and  the  flies  will  also  be  as  numerous  as  at  the 
sinks.  If  tlie  tubs  should  be  partially  filled  before  use 
with  a  disinfectant,  and  if  they  should  have  close-fitting 
covers  wliich  would  only  l)c  removed  at  the  time  of  use, 
the  o])jections  to  them  would  be  diminished,  but  would 
still  remain  in  part. 

The  board  of  medical  officers  already  referred  to  have 
recommended,  and  the  Surgeon-General  and  Adjutant- 
General  luive  adopted  the  recommendation,  that  the  ex- 
creta be  received  into  a  large  galvanized  iron  trough 
partially  filled  with  an  active  disinfectant  solution,  ])refer- 
ably  milk  of  lime  on  account  of  its  combined  efficiency 


INSTRUCTION  IN  HYGIENE.  439 

and  cheapness.  The  trongh  is  to  be  located  in  a  suitable 
building,  and  when  full  or  at  regular  intervals  is  to  be 
emptied  by  means  of  a  pumping  cylinder  into  a  large 
water-tight  tank  on  a  wagon,  similar  to  the  ordinary 
odorless  excavating  apparatus.  It  is  probable  that  such 
apparatus  under  proper  supervision  will  prove  as  efficient 
and  practicable  as  any  that  can  be  devised  short  of  a  well- 
constructed  system  of  sewers  involving  water-carriage,  the 
installation  of  which  is  obviously  not  feasible  in  a  tempo- 
rary camp  or  in  one  not  having  an  abundant  water- 
supply. 

Space  does  not  permit  of  a  full  discussion  of  military 
hospitals.  At  permanent  posts  they  may  have  almost  all 
the  equipment  and  conveniences  of  the  best  city  hospitals, 
but  in  the  field  in  actual  service  much  must  be  foregone. 
This  often  leads  to  censure  from  the  uninformed  and 
where  censure  is  not  deserved.  But  commanding  officers, 
especially  of  the  medical  service,  should  foresee  every 
emergency  and  provide  for  it  as  far  as  possible,  overrating 
rather  than  underrating  the  probable  needs  and  demands 
upon  the  hospital  staff,  and  providing  for  the  comfort  as 
well  as  the  necessities  of  the  sick  and  wounded.  The 
knowledge  that  typhoid  fever,  for  instance,  is  almost  cer- 
tain to  occur  and  become  epidemic  in  any  camp  of  con- 
siderable exteut  or  duration  should  compel  preparation 
for  the  proper  treatment  of  this  disease  in  so  far  as  this  is 
possible  in  a  field  hospital.  The  trained  nurse  has  proved 
her  value  in  army  hospital  work,  and  has  now  a  place  in 
the  regular  army  medical  service.  The  enlistment  and 
training  of  a  sufficient  number  of  hospital  stewards  is 
also  of  great  importance,  as  is  also  the  instruction  of  the 
soldiers  themselves  as  to  the  care  of  themselves  in  emer- 
gencies.    Undoubtedly  this  latter  instruction,  meagre  as 


440  MILITARY  HYGIENE. 

it  has  been,  and  tlie  "  first-aid  packets  "  with  which  each 
man  was  snpplied,  greatly  contributed  to  the  excellence 
of  results  among  the  regular  troops  in  the  late  war. 

A  thorough  course  in  the  fundamental  principles  of 
hygiene  should  be  a  part  of  the  education  of  every  soldier 
in  the  regular  army,  and  especially  should  this  subject  be 
established  as  one  of  the  most  important  in  the  curricu- 
lum at  West  Point.  If  the  graduates  and  future  officers 
from  this  great  military  school  were  so  instructed,  it  is 
more  than  probable  that  the  advice  and  suggestions  of 
the  medical  officers  of  the  service  would  be  more  often 
accepted  and  enforced  in  the  future  than  they  have  been 
in  the  past. 

Hospital  tents  are  apt  to  be  poorly  ventilated  and 
oppressive  in  hot  weather  or  climates.  They  should  have 
every  advantage  of  location,  that  the  comfort  as  well  as 
the  health  of  the  patients  may  be  conserved.  A  venti- 
lated hospital  tent,  devised  by  Captain  E.  L.  Munson, 
M.  D.,  U.  S.  A.,  has  been  adopted  by  the  Board  of 
Equipment  on  account  of  its  a<l vantages,  chief  of  which 
are  a  better  ventilation  and  a  lowering  of  the  temperature 
witliin  to  the  extent  of  several  degrees. 

Another  valuable  addition  to  the  hospital  service  of  the 
army  has  been  the  purchase  and  thorough  equipment  for 
the  purjiose  of  several  hospital  ships.  The  saving  of  life 
and  alleviation  of  distress  made  possible  by  these  vessels, 
when  compared  with  the  effects  of  conditions  obtaining  in 
the  ordinary  transport  ships,  are  incalculable. 

The  work  of  the  soldier,  Avhile  excessive  at  times,  ordi- 
narily permits  much  leisure  to  the  men,  which,  in  turn,  is 
conducive  not  only  to  attacks  of  homesickness  and  ennui, 
})ut  to  the  develo])ment  of  injudicious  and  injurious 
liabits.       Consequently,    anything     that    will    profitably 


DUTIES   OF  THE  MEDICAL    OFFICER. 


441 


employ  the  attention  and  activities  of  the  men  when  off 
dnty  is  beneficial.  For  this  purpose  reading-rooms, 
athletic  sports  and  the  work  of  various  trades  may  be 
mentioned.  This  need  furnishes  one  of  the  strong  argu- 
ments for  the  restoration  and  continuation  of  the  army 
canteen,  or  soldiers'  club.  This  question  involves  the 
treating  "with  human  nature  as  it  exists  in  the  army, 
rather    than    attempting    the    attainment  of    impossible 

Fig.  89. 


Muiison  ventilated  hospital  tent,  adopted  for  United  States  Army.    (The  fly 
thrown  back  over  false  ridge-pole  to  show  ventilation  opening  ) 

ideals,"  and  it  certainly  seems  that  the  favorable  reports 
and  commendation  of  the  very  great  majority  of  army 
officers  who  have  expressed  their  opinions  concerning  it, 
should  warrant  the  reestablishing  of  the  canteen.  At  any 
rate,  the  ability  to  keep  his  men  pleasantly  and  advantage- 
ously occupied  is  one  of  the  qualities  of  a  good  com- 
mander, and  medical  officers  should  assist  the  latter  in  this 
respect  whenever  possible. 


442  MILITARY  HYGIENE. 

The  medical  officer  will  also  be  watcliful  to  guard 
against  the  causes  of  the  diseases  which  are  most  preva- 
lent in  the  army,  viz.,  phthisis,  heart  disease,  pulmonary 
diseases,  typhoid,  malaria  and  continued  fevers,  and,  not 
least  in  importance,  venereal  diseases.  The  latter  do 
much  harm  in  most  standing  armies,  and  it  is  as  a  pro- 
phylactic to  these  that  the  occupation  of  time  and  energy 
referred  to  above  is  especially  advantageous.  So,  also, 
must  the  chief  surgeon  and  his  assistants  keep  oversight 
of  the  rations,  water-supplies,  etc.  They  must  inspect 
the  men  at  regular  intervals,  weighing  and  measuring 
them,  and  examining  for  heart-strain  or  other  circulatory 
disturbance ;  they  must  select  suitable  places  of  encamp- 
ment when  on  the  march,  caring  for  those  who  are  over- 
come by  the  heat  or  exhausted ;  they  must  see  that  the 
troops  do  not  injudiciously  expose  themselves  when  over- 
heated ;  in  fact,  they  must  be  fully  as  zealous  and  active 
as  the  commanding  officer  to  maintain  the  entire  com- 
mand in  its  highest  physical  efficiency. 

For  further  information  on  this  important  subject  the  reader  is  re- 
ferred to  the  article  on  "  Military  Hygiene  "  in  the  Reference  Handbook 
of  the  Medical  Sciences,  by  Colonel  A.  A.  Woodhull,  M.  D.,  and  to  the 
text-book  on  the  same  subject  by  Captain  Edward  L.  Munson,  M.  D., 
eacli  of  these  being  in  their  way  models  of  comprehensive  excellence, 
and  having  the  authority  of  practical  experience. 


CHAPTEE    XIY. 

VITAL  STATISTICS. 

Science  is  classified  knowledge.  By  arranging  kno'wn 
facts  and  units  into  groups,  and  considering  them  from 
different  points  of  view,  we  discover  the  scope  of  a  par- 
ticular science,  and  are  also  led  to  the  discovery  of  new 
tacts. 

In  hvo^iene  it  is  necessarv  to  have  this  classification  of 
facts  to  know  what  progress  we  are  making,  for  the  true 
test  of  any  sanitary  procedure  is  its  efficacy  in  preserving 
health  and  preventing  disease,  and  we  cannot  know 
whether  it  is  efficient  or  not  unless  we  tabulate  and  study 
the  results  and  at  the  same  time  eliminate  disturljing 
factors.  In  this  connection  it  is  to  be  noted  that  our 
facts  must  be  accurate  and  derived  from  sufficient  experi- 
ence, and  that  the  disturbing  factors  are  especially  liable 
to  be  numerous. 

It  is  evident  that  we  may  study  disease  by  direct 
observation  at  the  bedside  and  at  the  post-moHem  table,  or 
by  experiment ;  and  while  our  knowledge  in  the  past  has 
been  gained  principally  by  the  former  method,  we  now, 
since  the  advent  of  modern  ljacterioli)gy,  may  farther 
investigate  many  diseases  by  reproducing  them  in  sus- 
ceptible animals.  In  this  way  we  soon  learn  that  some 
diseases  are  much  more  preventable  than  others,  and  we 
endeavor  to  discover  the  respective  cau.ses  and  predispo.s- 
ing  conditions  of  each  that  we  may  the  more  readily 

443 


444  VITAL  STATISTICS. 

estimate  their  effects  and  take  measures  to  restrict  and 
prevent  their  action. 

Our  observations  may  be  of  two  kinds  :  1.  By  noting 
and  comparing  individual  cases,  or  by  following  the  track 
of  a  particular  outbreak  or  epidemic.  2.  By  observing 
large  classes  and  groups  of  men,  which  necessitates  a 
record  of  births,  marriages,  diseases,  and  deaths.  The 
consideration  of  such  records  constitutes  the  study  of 
vital  statistics,  the  most  important  object  of  which  is, 
as  Billings  says,  "  to  give  warning  of  the  undue  increase 
of  disease  or  death  presumed  to  be  due  to  preventable 
cause,  and  also  to  indicate  the  localities  in  which  sanitary 
effort  is  most  desirable  and  most  likely  to  be  of  use." 
The  reader  will  also  notice  how  the  study  of  vital  statistics 
broadens  out  into  the  science  of  demography — the  study 
of  the  life  of  people  and  communities. 

The  national  census  reports  now  give  statistical  returns 
not  only  for  the  wards  and  other  political  divisions  of 
some  of  our  large  cities,  but  also  for  so-called  "  sanitary 
districts,"  in  which  the  population  is  chiefly  made  up  of 
those  of  marked  racial  or  other  characteristics  that  in- 
fluence the  vital  problem.  Tlie  study  of  such  returns 
supplies  much  information  and  the  explanation  of  many 
otherwise  obscure  phenomena  in  the  vital  statistics  of  a 
municipality. 

At  this  point  it  will  be  well  to  note  certain  elementary 
princij)les  which  must  be  o]>served  in  any  statistical  in- 
quiry, in  order  that  tlie  results  of  that  incpiiry  may  liave 
any  value  whatever.     These  are  : 

1.  Our  facts,  or  numerical  units,  must  have  precise, 
definite,  and  constant  characteristics.  For  example,  in 
tabulating  the  death-rate  or  sick-rate  from  typhoid  fever, 
every  case    used  in   the    calculation   must  be    accurately 


OBJECT  OF  STATISTICAL  STUDY.  445 

diagnosed  and  mnst  be  undoubtedly  one  of  that  disease. 
If  there  is  any  doubt  as  to  preciseness,  it  is  better  to  omit 
that  unit. 

2.  The  units  are  to  be  arranged  into  groups.  These 
groups  must  have  dividing  characteristics  so  definite 
that  there  can  be  no  doubt  into  Mdiich  group  each  unit 
will  come.  No  unit  must  be  in  more  than  one  group 
at  one  time.  It  is  difficult  to  group  complex  facts  so 
as  to  analyze  them  properly  and  to  discover  all  possible 
phases. 

3.  Having  decided  and  arranged  the  groups,  we  must 
have  a  constant  numerical  standard  by  which  the  relation 
of  the  various  groups  to  the  total  units  may  be  expressed. 
It  is  generally  100  or  some  multiple  of  100. 

4.  We  must  determine  the  variation  in  the  proportion 
or  relation  of  the  component  groups  to  the  whole  in  similar 
series  of  cases.  While  only  an  approximation  to  an  inva- 
riable proportion  may  be  had  in  any  one  series,  it  may  be 
shown  mathematically  that  as  the  number  of  units  in  the 
series  increases  there  is  a  greater  probability  that  the  pro- 
portions will  remain  the  same,  and  that  we  may  calculate 
the  limits  of  variation  by  Poisson's  formula,  as  follows  : 
If  rii  be  the  number  of  units  in  one  group  in  the  formula 
7/1  +  n  =  g,  and  n  the  number  in  the  other,  the  propor- 
tion of  m,  to  q  will  be  -\  and  of  n  to  q,  -,  and  these  proi)or- 
tions  will  vary  in  succeeding  series  within  the  limits  indi- 
cated by  2  ^/ — -— .     Consequently,  the  greater  the  value 

of  q,  the  less  comparativelv  will  be  that  of  2^/ — -— ,  or  the 
limit  of  variation  from  —  and  - . 


446  VITAL  STATISTICS. 

Example:  Suppose  that  in  a  series  of  1000  cases,  of 
diphtheria  700  recover ;  tlien,  according  to  the  above 
formula,  the  limit  of  variation  in  the  next  series  of  1000 
similar  cases  "svould  be  40,  and  the  recoveries  would  be 
between  660  and  740 ;  whereas,  in  a  like  series  of  only 
100  cases  the  limit  of  variation  would  be  13  and  the 
probable  recoveries  would  vary  between  57  and  83. 

The  arithmetical  mean  is  usually  employed  in  medical 
inquiries,  though  the  increase  in  population  is  estimated 
by  geometrical  progression.  The  probable  error  or  varia- 
tion from  the  arithmetical  mean  is  about  two-thirds 
(0.6745)  of  the  mean  error,  which  latter  is  the  mean  of 
the  mean  error  in  excess  and  the  mean  error  in  deficiency. 
The  mean  error  in  excess  is  the  diiference  between  the 
mean  of  the  series  and  the  mean  of  all  the  units  of  the 
series  above  the  mean.  The  mean  error  in  deficiency  is 
the  diiference  between  the  mean  of  the  series  and  the 
mean  of  all  the  units  below  the  mean. 

The  relative  value  of  two  series  is  as  the  reciprocals  of 
the  squares  of  their  probable  errors.  Thus  if  the  probable 
error  of  series  A  is  10  per  cent,  and  that  of  B  is  2  per 
cent.,  the  value  of  A  to  B  will  be  as  ytto  ^^  i?  ^^  ^  will 
be  twenty-five  times  as  valuable  as  A. 

The  relative  value  of  two  or  more  series  is  also  as  the 
square  roots  of  the  numbers  of  units  in  the  respective 
series.  From  the  above  it  is  evident  that  the  results 
from  an  average  cannot  be  absolutely  applied  to  any  par- 
ticular case,  for  there  is  always  the  chance  of  such  varia- 
tion as  may  be  determined  by  Poisson's  formula  or  by  the 
estimation  of  the  ]>robable  error.  We  apjily  averages  to 
the  aggregates  of  facts,  and  they  will  approach  exactitude 
if  they  are  founded  on  a  sufficient  number  of  facts.  We 
nnist   be  careful   in   ('.-(iiiiatin<r  the   value  of  means  and 


NUMERICAL    UNITS. 


447 


averages  and  in  giving  credit  or  blame  accordingly.  Guy- 
says  :  "  Averages  are  numerical  expressions  of  proba- 
bilities ;  extreme  values  are  expressions  of  possibilities." 

Statistical  results  are  frequently  expressed  by  graphic 
representations  (see  Fig.  90),  and  these  are  very  valuable, 
especially  for  class  or  similar  demonstration. 

The  numerical  units  employed  in  the  study  and  the  cal- 
culations of  vital  statistics  are  persons  living  and  persons 

Fig.  90. 


7.0 
6.5 
6.0 
5.5 
5.0 

/ 

\ 

/ 

\ 

/ 

^ 

/ 

i 

/ 

\ 

4.0 
3.5 
3.0 
2.5 
"  fl 

/ 

/ 

\ 

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/ 
/ 

\ 

\ 

\ 

/ 

->^ 

/ 

\ 

; 

\ 

^ 

y 

^ 

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■^ 

^ 

^ 

^ 

/ 

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, 

'/ 

'' 

\; 

^ 

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\ 

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/' 

\, 

// 

— 

■V 

_,j 

, 

\ 

\ 

1.5 
1.0 

■^ 

^' 

\ 

> 

/' 

\ 

\ 

y 

■->., 

,- 

^^ 

-'' 

\ 

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^- 

^. 

^- 

■ — 

^- 

-~- 

X 

/ 

"■ 

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— 

~^. 

^^ 

.— 

— 

■* 



--■ 

0 

:>     - 

S    ; 

H       r 

S    1 

3  ; 

H        t 

I    I 

-t       1- 

-      c 

1 1 

i  I 

I 

-1       r 

\ 

\    % 

1  : 

H       r 

\        ( 

-t               *■ 

2   % 

3  ; 

3  % 

Graphic  chart,  showing  percentage.s  of  typhoiri-fever  deaths  in  total  mor- 
tality in  four  cities.  TJnhroken  line,  Chicago ;  lower  line,  New  York;  short 
dashes,  Philadelphia ;  long  dashes,  Boston. 


dead,  and  the  groups  into  which  these  units  are  classified 
are  characterized  by  such  distinctions  as  age,  sex,  occupa- 
tion, locality,  etc.  The  sources  from  which  we  derive  our 
information  regarding  these  units  are  two,  viz.,  the  census 
or  count,  which  every  civilized  country  makes  period- 
ically, and  the  returns  of  births,  marriages,  deaths,  and 


448  VITAL  STATISTICS. 

cases  of  contagious  disease  made  to  local  governing  sani- 
tary bodies,  such  as  boards  of  health,  etc.  These  latter 
returns  localize  the  units  and  help  especially  in  the  classi- 
fication in  which  locality  is  a  factor. 

The  census  returns  give  not  only  the  population,  but 
also  particulars  as  to  sex,  age,  race,  occupation,  etc.  Of 
these  the  age-record  is  most  important,  as  the  death-rate 
varies  most  according  to  age. 

The  natural  increment  of  a  population  is  the  excess  of 
births  over  deaths,  but  the  actual  increment  differs  from 
this,  however,  according  to  the  difference  between  emigra- 
tion and  immigration.  And  as  the  rate  of  increase  does 
not  always  remain  the  same,  estimates  of  population  at 
times  other  than  of  the  census  cannot  be  exactly  accurate. 
Thus,  we  may  have  a  lowered  death-rate  and  yet  a  de- 
crease in  both  the  natural  and  actual  increment,  owing  to 
a  greatly  lowered  birth-rate  and  to  increased  emigration, 
both  of  which  may  be  primarily  due  to  a  long  period  of 
oppression  or  financial  distress.  However,  to  estimate 
the  population  for  times  other  than  the  census  year,  we 
assume  that  the  rate  of  increase,  whether  positive  or  nega- 
tive, that  prevailed  between  the  last  two  census  enumera- 
tions will  continue  until  the  next  is  taken. 

Now,  as  populations  increase  in  regular  geometrical 
progression  when  the  rate  of  increase  is  constant,  which 
we  assume,  it  can  readily  be  shown  that 

logarithm  R  =  —  (log.  P'  —  log.  P),  Avhere  R  is  the 

annual  ratio  of  increase,  P  the  population  of  the  census 
before  the  last,  and  P'  the  po]Milation  of  the  last  census. 
If  we  now  nuiltiply  the  logarithm  of  R,  the  annual  ratio 
of  increase,  by  the  number  of  years  since  the  last  census, 
and  add  to  it  tlie  logarithm  of  the  last  census  (log.  P'), 


SOURCES  OF  INFORMATION.  449 

we   will    have    the   logarithm   of  the  population   at   the 
middle  of  the  given  year — e.g., 
(log,  of  the  pop.  1890  -  log.  pop^jSSO)  ^  .  -^g^Q 

10  '      &  1   F 

=  logarithm  of  the  population  on  June  30,  1 898. 

For  the  reasons  already  given,  such  an  estimate  will 
not  be  absolutely  accurate,  and  it  would,  consequently, 
be  well  to  have  a  census  taken  every  five  years  for  certain 
data.  The  more  accurate  the  estimate  for  any  year  hap- 
pens to  be,  the  mere  reliable  will  be  the  statistical  results. 
It  is  also  to  be  noted  that  in  this  country  the  census  is 
taken  at  the  middle  of  the  year,  and  that  death-rates,  etc., 
are  based  on  the  population  estimated,  as  above,  for  the 
middle  of  the  given  year. 

We  may  also  estimate  the  population  from  the  number 
of  houses  and  use  this  as  a  check  on  the  above  estimate. 
Tlie  number  of  persons  living  in  each  house  averages  about 
the  same  for  each  city,  but  differs  for  different  cities. 
Local  authorities  always  tend  to  overestimate  the  popu- 
lation, and  a  police  census  is  invariably  too  high.  An- 
other method  of  approximately  estimating  the  population 
in  small  and  slowly  increasing  districts  is  to  add  to  the 
population  of  the  last  census  one-tenth  of  the  difference 
between  it  and  the  population  of  the  preceding  census  for 
every  year  since  the  last  census. 

As  has  been  stated,  we  get  the  number  of  births,  mar- 
riages, deaths,  etc.,  from  the  registration  records,  the 
])r()per  data  being  furnished  to  the  registration  bureau  by 
duly  authorized  persons.  For  instance,  the  law  should 
require  a  burial  j)ermit  for  each  death  in  order  to  identify 
tlio  person  and  to  guard  against  criminal  acts  or  neglect, 
and  the  death  certificate  on  which  the  burial  permit  is 
issued  should  give  the  name,  sex,  color,  age,  occupation, 
29 


450  VITAL  STATISTICS. 

and  especially  the  cause  of  death  of  the  deceased.  The 
diagnosis  concerning  this  last  item  should  be  as  correct  as 
possible,  and  the  primary  as  well  as  the  secondary  cause 
of  death  should  be  given.  And  while  it  is  difficult  to 
determine  the  actual  cause  of  death  in  many  cases  without 
a  post-mortem  examination,  there  is  fortunately  not  much 
uncertainty  usually  in  diagnosing  the  diseases  of  which 
we  most  want  statistical  information,  especially  the  so- 
called  preventable  or  infectious  diseases. 

As  a  consequence  of  the  above,  the  certificate  as  to  the 
cause  of  death  will  need  to  be  signed  by  some  one  compe- 
tent to  determine  that  cause,  viz.,  by  an  educated  physi- 
cian ;  and  it  is  therefore  necessary  that  the  State  should 
define  who  is  and  who  is  not  an  "educated  physician." 
And  as  this  information  and  the  other  required  returns 
which  the  physician  makes,  as  well  as  his  professional 
services  in  general,  are  for  the  sake  and  benefit  of  the 
citizens  of  the  State,  it  is  evidently  to  the  State's  interest 
that  it  be  very  careful  and  explicit  as  to  the  qualifications 
of  the  physicians  whom  it  allows  to  practise  within  its 
borders. 

Another  reason  for  the  enforced  return  of  a  certificate 
and  the  issuance  of  a  burial  permit  for  every  death  is  that 
this  is  about  the  only  way  in  which  it  is  possible  to  secure 
a  record  of  all  the  deaths.  Any  system  for  collating  the 
list  of  d(>aths  only  at  the  end  of  the  year  will  omit  from 
25  to  40  per  cent,  of  the  niunber. 

The  statements  made  in  tlie  introductory  chapter 
and  clsowhoro  sliow  tlio  importance  of  vital  statistics 
in  determining  the  sanitary  conditions  and  improvement 
of  communities.  In  order  that  comparisons  and  correct 
judgmonts  may  be  readily  made,  it  is  evident  that  all 
classifications,  returns,  and  registrations  should  be  on  a 


VARIATION  OF  DEATH  BATE.  451 

basis  or  system  as  uniform  as  possible,  but  almost  the 
opposite  Las  obtained,  since  almost  every  State,  city,  or 
local  authority  has  used  its  own  system  and  without  any 
concert  of  action  until  comparatively  recently.  Accord- 
ingly, in  order  to  amend  this  and  to  secure  not  only  uni- 
form, but  also  correct  and  thorough  returns  from  the 
whole  country,  the  Division  of  Vital  Statistics  of  the 
U.  S.  Census  Office  is  making  extraordinary  effi^rts  to 
bring  about  uniform  legislative  requirements  in  the  vari- 
ious  States  and  to  secure  the  adoption  of  the  International 
Classification  of  Causes  of  Death,  which  is  intended  "  to 
harmonize  the  features  of  the  most  generally  used  systems 
in  order  to  afford  a  common  basis  of  union,"  and  has  been 
adopted  by  the  U.  S.  Census  Office  for  the  compilation  of 
mortality  statistics.  To  this  end  circulars  have  been  sent 
to  every  physician  "describing  the  details  required  by 
the  Standard  Certificate  of  Death  (see  next  page),  and 
giving  the  titles  of  the  International  Classification  of 
Causes  of  Death,  with  explanatory  notes  showing  the  sig- 
nificance of  various  terms  to  the  titles  under  which  they 
are  compiled,  and  a  list  of  indefinite  and  unsatisfactory 
terms  very  frequently  used  in  reporting  deaths,  with  a 
statement  of  why  such  statements  are  unsatisfactory." 
This  circular  is  very  instructive,  and  its  recommendations 
should  henceforth  be  observed  by  all  physicians  in  making 
death  returns.^ 

The  gross  death-rate  varies  wath  the  size  of  the  com- 
munity.    Newly  settled  communities  have  a  lower  death- 

'  This  circular  can  doubtless  be  had  on  application  to  the  Division  of 
Vital  Statistics  of  the  Census  Office  at  Washington,  together  with  a  cir. 
cular  on  Medical  Education  in  Vital  Statistics,  relating  to  the  instruc- 
tion of  medical  students  in  registration  methods,  uses  of  registration 
data,  and  the  duties  and  obligations  of  physicians ;  and  one  on  Practi- 
cal Registration  Methods,  for  the  information  of  local  registrars. 


8-209. 


MARGIN    RESERVED    FOR    BINDING. 


V.  S.  No.  98.         Write  Plainly,  with  Unfading  Ink— this  is  a  Permanent  Record. 

N.  B.— Every  item  of  information  should  be  carefully  supplied.  AGE  should  be 
stated  EXACTLY.  PHYSICIANS  should  state  CAUSE  OF  DEATH  in  plain 
terms,  that  it  may  be  properly  classified.  The  "Special  Information"  for 
persons  dying  away  from  home  should  be  given  in  every  instance. 


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452 


STATISTICAL   COMPUTATIONS.  453 

rate  tlian  older  ones,  because  the  proportion  of  adults  is 
larger  and  of  children  smaller  in  the  former.  With  large 
communities  and  short  periods  the  probabilities  of  error 
are  very  great,  and  the  longer  the  period  the  less  likelihood 
of  error.  Birth-rates,  marriage-rates,  and  death-rates  are 
usually  calculated  as  rates  per  thousand  of  the  population 
living  at  the  middle  of  the  given  year,  and  are  deter- 
mined by  multiplying  the  number  of  births,  marriages,  or 
deaths  by  1 000,  and  dividing  the  product  by  the  population. 

Fair  death-rates  are  9  to  16  per  1000  in  rural  districts 
and  small  villages;  14  to  18  per  1000  in  towns  of  5000 
to  20,000;  17  to  20  in  cities  of  25,000  to  100,000,  and 
18  to  21  in  cities  of  over  100,000.  If  the  death-rates  are 
much  lower  than  this,  the  chances  are  that  the  population 
has  been  overestimated  or  that  all  deaths  have  not  been 
recorded.  If  more  than  this,  there  is  probably  some 
special  cause  for  the  high  mortality.^ 

In  statistical  computations  we  must  exclude  the  popu- 
lations and  deaths  in  hospitals,  prisons,  etc.,  except  for 
such  of  the  inmates  as  belong  to  the  district  in  which 
such  institution  is  located. 

To  find  the  weekly  or  daily  death-rate,  the  number  of 

deaths  for  the  week  or  day  must  be  multiplied  by  1000 

and  divided  by  the  so-called  weekly  or  daily  population : 

,1  11  1  ,'  total  population     ,,      -,  ., 

the  weekly  population  = '^—'^ ;  the  daily  popu- 

'  These  rates  were  given  some  fifteen  or  more  years  ago  by  an  em- 
inent sanitary  authority,  and  they  still  hold  good  for  much  the  greater 
l)art  of  this  country.  However,  thanks  to  the  recent  advances  in  san- 
itation, such  as  the  use  of  antitoxin,  introduction  of  pure  water,  im- 
provement in  milk  and  food  supplies,  etc.,  certain  populations,  and 
especially  those  of  some  of  our  larger  cities,  have  succeeded  in  lower- 
ing the  mortality  rates  below  the  standard  given  and  in  maintaining 
them  at  points  which  would  have  been  deemed  impossible  a  score  of 
years  ago. 


454  VITAL  STATISTICS. 

latiou  = 1 — '- .    The  monthly  population  equals 

365.24226  ^  ^   ^  ^ 

the  daily  population  multiplied  by  the  number  of  days  in 

the  month. 

The  zymotic  death-rate  is  the  rate  from  the  seven 
principal  zymotic  or  infectious  diseases,  viz.,  smallpox, 
measles,  scarlatina,  diphtheria,  whooping-cough,  fever 
(typhoid,  typhus,  or  other  continued  fever),  and  diarrhoea.^ 
It  is  given  per  1000  of  population,  and  in  the  same  way 
we  can  give  the  sj^ecial  rate  for  any  particular  disease. 
For  example,  the  average  annual  zymotic  death-rate  for 
England  and  Wales  for  the  decade  from  1861  to  1870 
was  4.11,  for  1871-80  it  was  3.36,  and  for  1881-90,  2.30 
— a  striking  proof  of  the  decided  benefits  following  proper 
attention  to  hygiene  and  sanitation. 

The  mortality  from  certain  diseases  is  aifected  by  age, 
sex,  race,  occupation,  density  of  population,  seasons, 
cyclical  changes,  etc. 

Contrary  to  the  general  rule,  the  rate  of  infant  mortality 
is  not  expressed  per  thousand  of  population,  but  measured 
by  the  proportion  of  deaths  of  infants  under  one  year  to 
the  births  registered  in  that  year,  and  is  determined  by 
multiplying  the  number  of  deaths  by  1000  and  dividing 
the  product  by  the  number  of  births. 

The  infant  mortality-rate  is  always  high  owing  to 
various  causes,  viz.,  early  marriages  and  weakly  parents, 
hereditary  tendencies  or  diatheses,  insanitary  surroundings 
and  unfavorable  social  conditions,  improper  feeding,  in- 
suffifMcnt  clothing,  infant  life  insurance,  etc. 

Death-rates  vary  greatly  for  the  different  ages,  being 
much  In'gher  for  the  first  five  years  of  life.  For  this 
reason   it  is  well   to  express  the  death-rate  of  children 

>  Wilson,  Handbook  of  Hygiene,  8th  edition,  p.  570. 


FACTORS  AFFECTING  MORTALITY  RATES.      455 

under  five  as  the  rate  per  thousand  of  children  under  that 
age,  rather  tlian  as  a  percentage  of  the  total  number  of 
deaths.  Otherwise,  a  town  with  a  large  number  of  chil- 
dren might  apparently  have  an  abnormally  high  death- 
rate.  There  might  also  be  a  difference  in  the  death-rates 
of  two  localities  due  to  sex-distribution,  for  the  sexes 
differ  in  their  susceptibility  and  resistance  to  the  various 
diseases.  More  boys  are  born  everywhere  than  girls,  but 
more  males  die  than  females,  so  that  the  tendency  is  to  a 
preponderance  of  the  latter,  except  in  newly  settled  coun- 
tries or  localities.  Age-distribution  and  sex-distribution 
favor  a  low  mortality  in  rapidly  increasing  towns,  new 
localities,  and  manufacturing  districts ;  in  rural  districts 
they  tend  to  increase  the  death-rate. 

Consequently,  when  the  death-rates  of  two  or  more 
towns  or  localities  are  to  be  compared,  there  must  be  cor- 
rections for  age-distribution  and  sex -distribution.  The 
mean  annual  death-rate  of  the  country  for  the  decade  pre- 
ceding tlie  last  census  for  each  age  and  sex  is  applied  to 
the  town  or  district,  with  age-distribution  and  sex-distri- 
bution according  to  the  last  census.  The  total  number  of 
deaths  thus  calculated,  multiplied  by  1000,  and  divided 
by  the  population  of  the  last  census,  gives  the  standard 
death-rate  of  that  town.  The  mean  annual  death-rate  of 
the  country  divided  by  the  standard  death-rate  gives  the 
factor  for  correction,  which  being  multiplied  by  the  re- 
corded death-rate  of  any  year  gives  the  coi-rected  death- 
rate.  The  comparative  mortality  figure  is  determined  by 
multiplying  the  corrected  local  death-rate  by  1000  and 
dividing;  bv  the  death-rate  for  the  whole  country,  and 
ouly  indicates  that  the  same  population  which  gave  1000 
deaths  in  tlie  whole  country  gave  or  would  have  given  so 
many  deaths  in  the  town  or  district  in  question. 


456  VITAL  STATISTICS. 

The  morbidity-rate  or  sick-rate  of  a  community  is  diffi- 
cult to  estimate,  since  there  is  usually  no  complete  record 
and  registration  of  cases  of  disease.  Where  returns  are 
required  to  be  made  of  the  infectious-  diseases,  the  mor- 
bidity due  to  them  may  be  determined  in  the  same  way 
as  the  mortality  for  the  locality.  It  is  estimated  that 
there  is  a  total  of  about  two  years'  sickness  in  a 
community  for  every  death,  and  members  of  beneficial 
societies  are  said  to  average  about  one  and  one-half 
weeks'  sickness  annually.  In  this  connection,  the  fol- 
lowing definitions  are  given  of  terms  that  are  employed 
in  discussions  of  vital  statistics,  especially  in  relation  to 
longevity  : 

The  mean  age  at  death  of  a  population  is  the  average 
age  at  which  death  occurs  in  that  population,  and  is  indi- 
cated by  the  total  of  the  ages  at  death  divided  by  the 
number  of  deaths.  Inasmuch  as  it  depends  largely  on  the 
age-distribution  of  the  population,  it  is  neither  a  good  test 
of  longevity  nor  of  sanitary  conditions,  except  when  it  is 
calculated  or  taken  from  life-tables  for  an  entire  generation. 

The  probable  duration  of  life  is  the  age  at  which  any 
number  of  children  born  will  be  reduced  one-half,  the 
chances  thus  being  even  that  each  will  survive  to  that  age. 

For  a  million  children  the  probable  duration  of  life  is 
for  males  less  than  forty-five  years  ;  fi)r  females,  forty- 
seven  years. 

The  mean  duration  of  life  is  the  same  as  the  mean  age 
at  death  when  the  population  is  stationary  as  to  age- 
distribution  and  sex-distril)uti()n.  Otherwise,  it  is  indi- 
cated by  the  mean  after-lifetime. 

The  expectation  of  life  is  tlie  mean  after-lifetime  of  a 
person  at  any  age,  as  indicated  by  a  life-table ;  or,  in  other 
words,  it  is  the  average  number  of  years  which   persons 


DEFINITION  OF  TECHNICAL   TERMS.  457 

of  that  age  continue  to  live.  At  birth  it  is  identical  with 
the  mean  duration  of  life,  and  "as  applied  to  communi- 
ties, it  is  the  mean  lifetime  of  a  generation  of  persons 
traced  by  the  life-table  method  from  birth  to  death,  and 
is  the  only  true  test  of  the  health  of  populations."  Ac- 
cording to  Farr,  "a  life-table  is  a  barometer  which  in- 
dicates the  exact  measure  of  the  duration  of  life  under 
given  circumstances,  and  is  indispensable  in  gauging  the 
influence  of  sanitary  or  insanitary  conditions." 

The  essential  factors  of  a  life- table  are  the  number  and 
ages  of  the  living  and  the  number  and  ages  of  those  that 
die,  and  these  factors  are  obtained  from  the  mean  popu- 
lation for  each  age  and  sex  and  from  the  total  death- 
returns  between  two  censuses. 


CHAPTER    XV. 

THE  EXAMINATION  OF  AIR,  WATEE,  AND  FOOD. 

Ix  this  final  chapter  the  author  has  endeavored  to  ar- 
range a  series  of  methods  for  the  examination  or  analysis 
of  the  subjects  respectively  considered,  in  such  a  manner 
that  any  one  who  has  had  a  little  laboratory  experience 
may  be  enabled  to  determine  their  hygienic  conditions, 
sanitary  mfluence,  or  degree  of  purity,  and  this  at  the  cost 
of  a  minimum  of  time  and  expense. 

The  methods  outlined  have  been  selected  from  a  variety 
of  sources,  and  some  have  been  especially  modified  for  the 
purpose ;  so  that  while  it  is  not  claimed  that  they  will  give 
the  absolutely  accurate  results  desired  by  the  professional 
bacteriologist  or  chemist,  nor  that  they  will  suffice  as  a 
basis  for  expert  testimony  in  court  or  to  establish  legal 
rights,  it  is  believed  that,  if  carefully  carried  out,  they 
will  not  fail  to  yield  tlie  information  sought  for,  viz., 
whether  the  sample  of  air,  water,  or  food  examined  is 
sanitarily  pure  or  safe  for  use  within  the  accepted  limits. 

Only  such  apparatus  is  to  l)e  used  as  can  be  readily 
obtained  or  improvised  without  nuich  expense,  and  every 
effort  has  been  made  to  render  everything  clear  to  the 
student  and  reader,  so  that  he  may  not  hesitate  to  under- 
take the  necessary  investigation  whenever  occasion  requires 
or  an  o])portunity  offers. 

For  further  details  regarding  any  of  the  methods,  should 
these  be  found  necessary,  reference  may  be  made  to  the 

458 


AIR.  459 

text-books  indicated,  as  they  will  render  clear  any  points 
that  may  here  seem  uncertaui  or  abstruse. 

Air. 

The  solid  impurities  in  the  atmosphere  may  be  col- 
lected for  microscopical  examination  as  follows :  Tightly 
cork  a  large  glass  funnel  and  fill  it  with  cracked  ice.  As 
the  aqueous  vapor  of  the  air  condenses  on  the  exterior, 
the  dust  particles  adhere  to  the  moistened  glass,  and  are 
carried  down  by  the  condensed  ^^ater  into  a  vessel  placed 
below,  iu  which  they  are  allowed  to  settle.  From  this 
they  are  transferred  by  means  of  a  pipette  to  clean  slides 
and  examined  under  the  microscope.  Dixon's  apparatus 
may  often  be  used  advantageously,  especially  where  it  is 
desired  to  examine  the  dust  in  the  air  of  a  number  of 
localities  within  a  short  time.  In  this  the  air  from  the 
respective  places  is  drawn  successively  over  cover-glasses 
which  have  been  coated  with  gelatin  or  glycerin,  and  on 
which  the  dust  particles  are  deposited  and  adhere  till  they 
may  be  examined  microscopically  or  bacteriologically. 

To  make  a  qualitative  bacteriological  examination  the 
air  may  also  be  drawn  through  sterilized  glass  tubes  coated 
interiorly  with  gelatin.  Bacteria  and  their  spores,  moulds, 
etc.,  adhere  to  this  coating,  and  from  each  individual  or 
group  of  individuals  colonies  develop,  from  which  pure 
cultures  and  subsequent  bacteriological  experiments  may 
be  made ;  or  the  sterilized  gelatin  may  be  exposed  in  flat 
(Petri)  dishes  to  the  air  for  a  short  time  to  allow  the  bac- 
teria, etc.,  to  fall  on  the  surface.  The  tubes  or  dishes  are 
then  covered  and  set  aside  to  allow  the  colonies  to  develop. 

To  make  a  quantitative  bacteriological  examination  a 
known  quantity  of  air  may  be  drawn  through  a  small 
tube    filled  with   sterilized   and   pulverized    sugar.     The 


460   THE  EXAMIXATIOX  OF  AIR,    WATER,  AXD   FOOD. 

sugar  is  then  transferred  to  tubes  or  flasks  of  melted  and 
sterilized  gelatin,  and  dissolving  leaves  the  bacteriaj  etc., 
free  to  develop  in  the  gelatin,  ^vhich  may  be  poured 
upon  sterilized  glass  plates  or  Petri  dishes  before  cooling. 
A  temperature  just  sufficient  to  melt  the  gelatin  ^vill  not 
be  too  warm  to  harm  the  bacteria.  The  number  of  colo- 
nies that  develop  maybe  assumed  to  represent  the  number 
of  living  micro-organisms  in  the  volume  of  air  drawn 
through  the  tube. 

Test  for  Carbon  Dioxide,  COo. — Boom's  Jlodi- 
jicatioii  of  Woljje/'fs  Method. — Make  a  mark  on  any  test- 
tube,  say  one  inch  from  the  bottom.  Fix  the  bulb  of 
an  atomizer  to  a  glass  capillary  tube  sufficiently  long 
to  reach  to  the  bottom  of  the  test-tube,  and  in  such  a 
manner  that  a  definite  quantity  of  air  is  forced  from  the 
bulb  through  the  tube  at  each  compression.  To  use :  Fill 
the  test-tube  exactly  to  the  mark  with  a  saturated  solu- 
tion of  lime-water,  take  the  apparatus  into  tlie  out-door 
air  and  find  out  how  many  compressions  of  the  luill)  are 
needed,  driving  the  air  sloAvly  through  the  lime-water 
each  time,  to  make  the  lime-water  just  turljid  enough  to 
obscure  a  pencil-mark  on  white  paper  placed  beneath  the 
test-tube  and  viewed  from  above.  Then  rinse  out  the 
test-tube,  fill  exactly  to  the  mark  again  with  lime-water, 
and  repeat  the  process  in  the  room  the  :iir  of  wliieh  is  to 
be  examined.  AVe  then  assume  tlnit  tiie  ont-door  air  C(M1- 
tains  the  normal  amount  of  carl^on  dioxide — 0.04  per  cent. 
(unless  we  happen  to  know  tlie  aetiinl  ainoiint  in  tlie  atmos- 
phere at  the  time),  and  estimate  tlie  jiercentage  of  carlxni 
dioxide  in  the  air  of  the  room  by  the  following  proportion  : 
Let  X  =  the  percentage  of  COg  in  the  air  of  the  room.  Tlien 
the  nnmher  of  coinpreftsions  of  the  bulb  reqnired  in  the  oider 
air  i.H  to  the  number  of  eom])resfdonH  required  in  the  room  as 


TEST  FOR   CARBON  DIOXIDE  IN  AIR.  461 

X  is  to  0.04.  If  the  actual  percentage  of  CO2  in  the  outer 
air  is  known,  substitute  this  for  the  0.04  per  cent,  in  the 
formula.  Care  must  be  taken  in  using  this  device  not  to 
draw  any  of  the  lime-water  into  the  bulb. 

A  JlocUJication  of  Angus  Smith's  Jlethod. — To  a  mod- 
erately large,  wide-mouth  bottle  (one  quart)  fit  a  per- 
forated rubber  stopper,  the  perforation  being  just  large 
enough  to  admit  the  tip  of  a  1  c.c.  pipette ;  first  fill  the 
bottle  with  the  air  of  the  room  by  filling  it  with  water 
and  then  emptying  it  in  the  room ;  fit  in  the  stopper  and 
introduce  1  c.c.  at  a  time  of  a  standardized  alkaline 
solution,  slightly  colored  with  a  few  drops  of  a  neutral 
alcoholic  solution  of  phenolphthalein ;  close  the  perfora- 
tion with  a  piece  of  glass  rod  and  shake  the  bottle  well 
after  each  addition  of  the  alkali,  noting  when  the  color 
ceases  to  be  discharged  by  the  CO2  of  the  contained  air. 
Then,  since  the  quantity  used  of  the  alkali  solution  indi- 
cates a  certain  definite  amount  of  COg : 

The  number  of  c.c.  of  solution  used  multiplied  by  the 
amount  of  CO.^  each  c.c.  re-presents.,  multiplied  by  100, 
and  divided  by  the  capacity  of  the  bottle  in  c.c.  less  the 
number  of  c.c.  of  solution  used  ^=x  =  the  percentage  of 
CO2  in  the  air  examined. 

A  suitable  alkaline  solution  may  be  prepared  as  fol- 
lows :  Dissolve  exactly  2.409  grammes  of  pure  sodium 
carbonate  (free  from  the  water  of  crystallization)  in  1 
litre  of  distilled  water.  Only  a  fraction,  say  one-fourth 
(jr  one-tenth,  of  this  quantity  need  be  made  up  at  a  time. 
Each  c.c.  of  this  solution  is  equivalent  to  1  c.c.  of  CO,. 
For  use :  To  10  c.c.  of  this  solution  add  a  few  drops  of 
neutral  alcoholic  solution  of  })henolp]ithalein  and  dilute 
to  100  c.c.  Each  c.c.  of  this  dilute  solution  is  then 
equivalent  to  0.1  c.c.  of  CO,,  and  used  as  above  will  give 


462  THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD. 

close  results.  The  phenolphthalein  is  used  as  an  indi- 
cator, as  it  loses  its  color  as  long  as  the  COg  is  absorbed 
and  the  alkalinity  of  the  soda  solution  is  destroyed.  The 
stock  solution  should  be  kej)t  in  well-filled,  tightly  stop- 
pered bottles. 

Example  :  If  9  c.c.  of  the  above  dilute  solution  be  used, 
and  the  capacity  of  the  bottle  is  1200  c.c,  then 

9  X  0.1  X  100 90^  _    _     ^ 

1200-9     "1191""^      0.075&, 

the  percentage  of  CO2  in  the  air  of  the  room. 

Pettenkofer' s  Method. — Into  a  large  clean  bottle  filled, 
as  above,  with  the  air  of  the  room,  50  c.c.  of  a  clear  solu- 
tion of  lime  (or  barium  hydrate)  are  introduced,  the  bottle 
stoppered  and  then  well  shaken  so  that  the  air  may  be 
thoroughly  mixed  with  the  lime-water.  The  strength  of 
the  lime-water,  being  unknown,  is  determined  by  means 
of  a  solution  of  oxalic  acid  of  such  a  strength  that  1  c.c. 
corresponds  in  alkalinity  to  0.5  c.c.  of  CO,.  (Such  a 
solution  is  made  by  dissolving  exactly  2.84  grammes  of 
pure  crystallized  oxalic  acid  in  1  litre  of  distilled  water.) 

Into  25  c.c.  of  the  stock  lime-water  in  a  beaker  this 
acid  solution  is  run  from  a  graduated  burette  until  the 
alkalinity  of  the  lime-water  is  just  destroyed,  the  neutral 
point  being  indicated  either  by  means  of  a  few  drops  of 
phenolphthalein  solution  in  the  beaker  or  by  turmeric 
paper,  the  latter  being  colored  brown  and  the  phenol- 
phthalein retaining  its  color  as  long  as  the  solution  is 
alkaline.  When  the  lime-water  is  exactly  neutralized,  the 
exact  amount  of  the  acid  solution  used  is  noted.  Then, 
after  the  time  necessary  to  allow  the  complete  absorption 
of  the  CO2  in  the  testing  bottle  by  the  lime-water  therein, 
viz.,  eight  to  ten  liours,  25  c.c.  of  that  lime-water  are 
measured    into    a    beaker,    and    the    alkalinity    exactly 


< 


PETTENKOFER'S  METHOD.  463 

determined  as  above  by  means  of  the  oxalic  acid  solu- 
tion. 

Now,  inasmuch  as  part  of  the  alkalinity  of  the  lime- 
water  which  was  in  the  bottle  has  already  been  neutral- 
ized by  the  carbon  dioxide  in  the  air  of  the  bottle,  it  will 
require  less  of  the  acid  solution  to  neutralize  the  lime- 
water  from  the  bottle  than  was  required  for  the  same 
quantity  of  stock  lime-water,  and  as  1  c.c.  of  the  acid 
solution  corresponds  to  0.5  c.c.  of  CO2,  the  difference  in 
the  amounts  of  acid  solution  used  expressed  in  c.c.  will 
express  the  number  of  c.c.  of  CO2  in  the  volume  of  air 
in  the  bottle. 

For,  though  each  c.c.  of  acid  solution  is  equivalent  to 
only  0.5  c.c.  of  COg,  the  loss  of  alkalinity  of  only  one- 
half  the  lime-water  primarily  introduced  into  the  bottle 
has  been  determined,  and  the  total  loss  of  alkalinity  would 
have  to  be  expressed  by  multiplying  0.5  c.c.  COj  by  tivice 
the  diiference  in  c.c.  between  the  amount  of  acid  used  in 
testing  the  stock  lime  solution  and  that  used  in  testing 
the  25  c.c.  (one-half)  of  lime-water  from  the  bottle.  But 
twice  0.5  =  1.  Therefore,  the  difference  between  the 
readings  in  the  two  tests  gives  the  amount  of  CO2  in  the 
bottle  having  been  thus  determined  and  the  capacity  of 
air  in  the  bottle.  The  quantity  of  carbon  dioxide  in  the 
bottle  having  been  thus  determined  and  the  capacity  of 
the  bottle  found  by  measuring  the  quantity  of  water  it 
will  hold,  the  percentage  of  carbon  dioxide  in  the  air  ex- 
amined is  readily  determined. 

Example :  25  c.c.  of  stock  lime-water  require  30  c.c. 
acid  solution ;  25  c.c.  of  lime-water  from  bottle  require 
27  c.c.  of  acid  solution. 

Therefore,  30  c.c.  —  27  c.c.  =;  3  c.c.  =  amount  of  carbon 
dioxide  that  was  in  the  air  in  the  bottle,  which  latter  con- 
tains (for  example  say)  2550  c.c. 


464  THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD. 

Then    3X100  ^  300^^q.i2  per  cent.  CU  in  the 
2550  —  50      2500  ^  ' 

air  of  the  room  at  current  temperature  and  pressure.  To 
be  absohitely  exact  in  the  result,  correction  must  be  made 
by  reducing  the  results  to  the  standard  temperature  and 
barometric  pressure,  but  this  is  unnecessary  in  most  cases. 
The  absorption  of  the  carbon  dioxide  gas  is  more  rapid 
if  a  solution  of  barium  hydrate  is  used  instead  of  the 
lime-water,  the  former  taking  up  the  gas  in  an  hour  or  so 
instead  of  eight  or  ten,  as  with  the  lime-water,  but  the 
latter  is  usually  much  more  readily  obtained,  and  there- 
fore more  hkely  to  be  used. 

Water. 

To  test  for  color,  turbidity,  etc.,  compare  %vith  distilled 
water,  using  tall  glass  jars  and  looking  down  through 
equal  depths  upon  a  white  surface.  The  smell  of  a  water 
may  be  detected  by  heating  it  to  about  140°  F.  for  a  few 
minutes  in  a  glass-stoj^pered  bottle.  This  test  may  or 
may  not  indicate  fecal  contamination.  Few  polluting 
impurities,  when  only  in  moderate  quantities,  give  any 
taste  to  water,  and  a  dangerously  polluted  water  may 
have  a  good  taste.  Iron  in  small  quantities,  one-fourth 
of  a  grain  to  a  gallon,  will  give  a  taste  to  the  water. 

Use  caution  in  tasting  suspicious  waters.  Aeration  is 
indicated  l)y  the  lustre  of  the  Avater  and  by  the  presence 
of  air-bubl)les  on  the  sides  and  bottom  of  the  vessel.^ 

Test  for  Chlorine. — Solutions  required:  1.  Standard 
nitrate  of  silver  solution  :  to  1  litre  of  pure  distilled  water 
add  4.788  grammes  of  pure  silver  nitrate  ;  1  c.c.  of  this 
solution  is  equivalent  to  1  m.g.  of  chlorine.  2.  Potas- 
sium chromate  solution — a  5  or  10  per  cent,  solution  of 

1  See  also  pages  205  to  210. 


TEST  FOR   CHLORINE  IX    WATER. 


465 


potassium  chromate  made  up  iu  distilled  water  free  from 
chloriue. 

Process. — To  100  c.c.  of  the  water  add  a  feAv  drops  of 
potassium    chromate   solution,   and    then  run   in   from    a 


Fig.  91. 


IBj^ENTSSiSDNS 


iMi 


Bottle  for  collecting  samples  of  water  at  different  levels. 

Ijurette  or  graduated  pipette  the  silver  solution,  adding  it 
drop  by  drop,  and  stirring  the  water  with  a  glass  rod. 
Continue  until  a  faint  but  permanent  orange-red  tint  has 
30 


466    THE  EXAMINATION   OF  AIR,   WATER,  AND  FOOD. 

been  produced,  showing  that  all  the  chlorine  has  combined 
M'ith  the  silver,  the  persistent  reddish  color  being  due  to 
silver  chroraate.  The  number  of  c.c.  of  silver  solution 
used  indicates  the  number  of  milligrammes  of  chlorine  in 
100  c.c,  or  parts  per  100,000;  this  multiplied  by  10  gives 
the  number  of  milligrammes  in  1  litre,  or  parts  per 
1,000,000.  If  the  water  contains  but  little  chlorine, 
accuracy  will  be  furthered  by  evaporating  250  c.c.  of  the 
water  to  50  c.c.  over  a  Avater-bath,  and  proceeding  as 
above ;  the  result  multiplied  by  4  will  give  the  amount 
of  chlorine  in  1  litre. 

Test  for  Nitrates. — Solutions  required:  1.  Pheuol- 
sulphonic  acid:  6  grammes  of  pure  carbolic  acid;  37  c.c. 
of  strong  sulphuric  acid,  and  3  c.c.  of  distilled  water.  2. 
Standard  potassium  nitrate  solution  :  add  0.722  gramme 
of  fused  potassium  nitrate  to  1  litre  of  distilled  water. 
Each  c.c.  of  this  solution  contains  0.1  m.g.  of  nitrogen  as 
nitrates.  The  water  used  in  making  the  solution  must  be 
free  from  nitrates. 

Process. — Evaporate  10  c.c.  of  the  water  to  be  exam- 
ined (or  25  c.c.  if  it  is  presumably  low  in  nitrates)  just  to 
dryness.  Add  1  c.c.  of  phenolsulphonic  acid,  stir  with  a 
glass  rod,  and  add  1  c.c.  of  distilled  water  and  3  drops  of 
strong  sulphuric  acid  ;  warm,  and  add  25  c.c.  of  distilled 
"vvater,  being  careful  througliout  the  test  not  to  dissociate 
and  drive  off  any  of  the  nitrates  by  too  prolonged  or  in- 
tense heating ;  then  add  ammonia  until  the  fluid  is  strongly 
alkaline,  and  dilute  with  water  to  50  c.c. 

Treat  1  c.c.  of  tlie  standard  solution  in  an  exactly 
similar  manner  and  compare  the  tints  produced,  jjlacing 
them  in  two  Nessler  or  other  tubes  of  equal  calibre,  and 
diluting  the  darker  until  the  tints  match  exactly,  and  cal- 
culating tlie  amount  of  nitrogen  present  by  the  amount  of 


TEST  FOR  NITRITES  IX   WATER.  4G7 

dilution  necessary — e.  </.,  in  testing  a  certain  sample,  the 
tint  from  1  c.c.  of  standard  potassium  nitrate  solution  is 
darker  and  requires  the  addition  of  50  c.c.  more  water 
— i.  €.,  up  to  100  c.c.  Therefore,  100  c.c.  :  50  c.c. 
: :  0.1  m.g.  N  :a;  =  0.05  m.g.,  the  amount  of  nitrogen  as 
nitrates  in  the  10  c.c.  of  water  examined.  The  test  is  based 
on  the  facts  that  some  of  the  phenolsulphonic  acid  is  con- 
verted by  the  nitrates  into  picric  acid,  which  forms  am- 
monium picrate  upon  addition  of  the  ammonia  and  gives 
a  yellow  tint  to  the  Avater,  and  that  the  amount  of  picric 
acid  and  picrate  formed  and  the  consequent  depth  of  color 
depend  on  the  amount  of  nitrates  present  in  the  water. 

Test  for  Nitrites. — Solutions  required:  1.  Sulphanilic 
acid  :  dissolve  0.5  gramme  ol  sulphanilic  acid  in  150  c.c. 
of  dilute  acetic  acid,  sp.  gr.  104.  2.  Naphthylaraine 
acetate  :  boil  0.1  gramme  of  solid  naphthylamine  in  20 
c.c.  of  distilled  water,  filter  through  a  plug  of  washed 
absorbent  cotton,  and  mix  the  filtrate  with  180  c.c.  of 
dilute  acetic  acid.  3.  Standard  sodium  nitrite  solution : 
dissolve  0.275  gramme  of  pure  silver  nitrite  in  pure  water 
and  add  a  dilute  solution  of  pure  sodium  chloride  until  a 
precipitate  ceases  to  form,  and  dilute  to  250  c.c.  with  pure 
water.  For  use,  dilute  10  c.c.  of  this  stock  solution  to  100 
c.c.  Each  c.c.  of  the  dilute  solution  contains  0.01  m.g. 
of  nitrogen  as  sodium  nitrite.  Keep  the  solutions  in  the 
dark  when  not  in  use.  All  water  in  these  solutions  must 
be  free  from  nitrites ;  likewise  all  water  used  in  the  tests, 
except  the  sample  under  examination. 

Process. — Place  25  c.c.  of  the  water  to  be  examined  in 
a  cylindrical  vessel,  and  in  a  similar  vessel  of  the  same 
calibre  dilute  1  c.c.  of  the  (diluted)  standard  sodium  nitrite 
solution  to  25  c.c,  with  nitrogen-free  distilled  w\ater ;  add 
to  each  vessel  2  c.c.  of  first  one  and  then  the  other  reagent, 


468   THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD. 

using  a  separate  pipette  for  each  ;  compare  the  colors  at  the 
end  of  five  minutes  and  estimate  the  amount  of  nitrites  by 
dihiting  the  darker  tint  until  it  matches  the  lighter,  and 
comparing  the  respective  volumes,  as  in  the  test  for 
nitrates ;  the  result  will  give  the  quantity  of  nitrogen  as 
nitrites  in  the  water,  and  should  not  be  more  than  a  trace. 
The  above  test  is  a  very  delicate  one. 

Schuyten's  3Iethod} — "  When  5  c.c.  of  a  1  per  cent, 
solution  of  antipyrin  in  acetic  acid  (1  :  10)  is  added  to  a 
solution  containing  nitrites,  a  green  color  is  produced." 
Measure  45  c.c.  of  the  water  to  be  examined  into  a 
Nessler  tube,  and  in  another  of  equal  calibre  mix  1  c.c. 
of  the  standard  sodium  nitrite  solution  (dilute)  with  44 
c.c.  of  distilled  and  nitrite-free  water.  To  each  tube  add 
5  c.c.  of  the  antipyrin  solution.  Allow  to  stand  for  one- 
half  hour  and  compare  as  above. 

"  This  method  will  show  the  presence  of  1  part  of 
nitrogen  as  nitrous  oxide  in  20,000  parts,  and  wliile  not 
so  delicate  as  the  other  method,  is  not  hindered  by  tlie 
presence  of  any  of  the  ordinary  contaminations  in  water."  ^ 

Test  for  Hardness. — Solutions  required :  1.  Soap  solu- 
tion :  dissolve  10  grammes  of  castile  soap  in  1  litre  of 
weak  (35  per  cent.)  alcohol.  2.  Standard  lime  solution  : 
dissolve  1.11  grammes  of  chemically  pure  calcium  chlo- 
ride in  1  litre  of  distilled  water :  1  c.c.  of  this  solution 
is  equivalent  to  1  m.g.  of  calcium  carbonate. 

Process. — Ascertain  how  much  soap  solution  is  required 
to  malvc  a  standard  lather  with  100  c.c.  of  distilled  water, 
as  follows  :  Place  the  water  in  a  flask  holding  about  250 
c.c,  and  run  in  the  soap  solution  from  a  burette,  a  few 
drops  at  a  time,  corking  and  shaking  the  flask  well  after 
each  addition  ;  tlie  lather  should  have  a  depth  of  at  least 
^  Bergey's  I-Iancll)ook  of  Practical  Hyf^iene,  p.  95.  ^  Ibid. 


TESTS  FOR  LEAD,  COPPER,  AND  IRON  IN  WATER.  469 

one-fourth  of  an  inch  and  be  permanent  for  not  less  than 
live  minutes.  Then  standardize  tlie  soap  solution  by  dilut- 
ing 5  c.e.  of  the  standard  lime  solution  to  100  c.c.  with  dis- 
tilled water,  and  determine  how  many  c.c.  of  the  soap 
solution  are  required  to  make  a  permanent  lather  as 
above  with  it;  this  quantity,  less  the  number  of  c.c. 
needed  to  make  a  lather  with  100  c.c.  of  distilled  water, 
represents  the  amount  of  soap  solution  that  will  neutral- 
ize 5  m.g.  of  calcium  carbonate  or  its  equivalent.  Lastly, 
determine  in  the  same  way  the  number  of  c.c.  of  soap 
solution  necessary  to  make  a  permanent  lather  with  100 
c.c.  of  the  water  to  be  examined ;  again  subtract  the 
quantity  of  soap  solution  requisite  to  make  a  lather 
with  100  c.c.  of  distilled  water,  and  estimate  the  amount 
of  calcium  carbonate  or  its  equivalent  present,  as  fol- 
lows— e.  g.,  it  takes  2  c.c.  of  soap  solution  to  make 
a  lather  with  the  distilled  water,  and  12  c.c.  with  the 
diluted  standard  lime  solution;  then  12  c.c.  —  2  c.c.  = 
10  c.c,  which  is  equivalent  to  5  c.c.  of  the  standard  lime 
solution,  and  accordingly  each  c.c.  of  the  soap  solution  is 
equivalent  to  0.5  c.c.  of  the  standard  lime  solution,  or  to 
0.5  m.g.  of  calcium  carbonate  ;  consequently,  if  100  c.c.  of 
the  water  examined  require  17  c.c.  of  soap  solution,  it 
must  contain  (17  —  2)  X  0.5  =  7.5  m.g.  of  calcium  car- 
bonate or  its  equivalent,  or  75  m.g.  to  the  litre. 

Tests  for  Lead,  Copper,  and  Iron.— To  50  or  100  c.c. 
of  water  in  a  white  porcelain  dish,  or  in  a  tall  glass  jar 
over  white  paper,  add  a  few  drops  of  ammonium  sul- 
phide ;  a  dark  coloration  or  precipitate  indicates  the  pres- 
ence of  either  lead,  copper,  or  iron,  due  to  formation  of 
their  respective  sulphides.  Then  add  a  few  drops  of 
hydrochloric  acid  :  if  the  color  disaj^pears,  iron  only  is 
present ;  if  it  persistSj  lead  or  copper  is  present.     In  the 


470   THE  EXAMINATION  OF  AIR,   WATER,  AND  FOOD. 

latter  case  add  a  few  drops  of  acetic  acid  and  about  1  c.c. 
of  a  strong  solution  of  potassium  cyanide  :  if  the  color 
disappears,  it  is  due  to  copper ;  if  it  persists,  it  is  due  to 
lead.  If  lead  only  is  present,  the  above  test  will  detect 
one-tenth  of  a  grain  per  gallon.  The  above  tests  may  be 
corroborated  as  follows :  Partly  fill  two  test-tubes  with 
the  original  water.  To  one  add  a  little  potassium  chromate 
solution  :  an  opacity  and  the  deepening  of  the  color  to 
canary  yellow  indicate  lead.  To  the  second  add  a  drop 
of  hydrochloric  acid  and  a  few  drops  of  potassium  ferro- 
cyanide  solution  :  a  blue  color  indicates  iron,  in  either  the 
ferrous  or  ferric  form  ;  a  bronze  or  mahogany-red  color 
indicates  copper. 

Quantitative  tests  for  the  above  metals  may  be  made  by 
making  standard  solutions  of  the  respective  elements  or 
some  of  their  salts,  treating  a  measured  quantity  of  the 
original  water  with  the  proper  reagent  as  indicated  above, 
and  comparing  the  color  produced  with  that  given  by  a 
definite  quantity  of  the  respective  standard  solution. 

Test  for  Phosphates. — Solutions  required :  Ammonium 
molybdate  :  dissolve  10  grammes  of  molybdic  anhydride 
in  41.7  c.c.  of  ammonia  (sp.  gr.  0.96)  and  pour  slowly 
into  125  c.c.  of  nitric  acid  (sp.  gr.  1.20) ;  allow  to  stand 
in  a  warm  place  for  several  days  until  clear. 

Process. — Slightly  acidulate  500  c.c.  of  water  with 
nitric  acid,  evaporate  to  50  c.c,  and  add  a  few  drops  of 
ferric  chloride  and  ammonia  to  slight  excess  ;  filter,  dis- 
solve the  precipitate  in  the  smallest  possible  quantity  of 
nitric  acid  and  evaporate  to  5  c.c;  heat  nearly  to  Iwiling, 
add  20  c.c.  of  ammonium  molybdate  solution  ;  keep  the 
solution  warm  for  one-lialf  hour.  If  there  is  an  appreci- 
able quantity  of  jirecipitate,  collect  it  on  a  small  weighed 
filtor-]>aper,  wash  with  distilled  water,  dry  at  100°  F.,  and 


TEST  FOR   AMMONIA   IN   WATER.  471 

weigh.  The  weight  of  the  precipitate  multiplied  by  0.05 
gives  the  amount  of  phosphorus  tetroxicle  (PO^)  in  the 
500  c.c.  of  water. 

Test  for  Free  and  Albuminoid  Ammonia. —  Wank- 
lyn's  Method. — Solutions  i-equired :  1.  Standard  ammo- 
nium chloride  solution  :  dissolve  0.382  gramme  of  pure 
dry  ammonium  chloride  in  100  c.c.  of  ammonia-free  water. 
For  immediate  use  dilute  10  c.c.  of  this  standard  stock 
solution  up  to  100  c.c.  with  ammonia-free  water;  each 
c.c.  of  the  dilute  solution  contains  0.01  m.g.  of  nitro- 
gen as  ammonia.  2.  Alkaline  potassium  permanganate 
solution  :  dissolve  200  grammes  of  potassium  hydrate  (in 
sticks)  and  8  grammes  of  potassium  permanganate  in  1 
litre  of  distilled  water,  evaporate  to  about  750  c.c.  to 
drive  oflP  the  ammonia  present,  and  make  up  to  1  litre 
again  with  ammonia-free  water.  To  make  ammonia-free 
water,  add  about  1  grain  of  sodium  carbonate  to  1  litre  of 
distilled  water  and  boil  until  about  one-fourth  is  evapor- 
ated. 3.  Nessler's  reagent :  dissolve  1.5  grammes  of 
potassium  iodide  in  10  c.c.  of  distilled  water  and  1.7 
grammes  of  mercuric  chloride  (HgCl2)  in  30  c.c.  of  dis- 
tilled water ;  add  the  mercuric  chloride  solution  to  the 
potassium  iodide  until  a  permanent  precipitate  is  formed, 
and  then  dilute  to  100  c.c.  with  a  20  per  cent,  solution 
of  sodium  hydrate,  add  the  mercuric  chloride  solution  till 
a  permanent  precipitate  again  forms,  and  allow  to  stand 
until  clear;  this  reagent  gives  a  brown  or  yellowish-brown 
coloration  if  ammonia  be  present  in  water,  and  improves 
on  keeping. 

Process. — Place  in  a  retort  500  c.c.  of  the  water  to 
be  examined,  connect  with  a  condenser,  and  boil  gently 
so  that  the  water  may  distil  over  slowly.  The  retort 
and  condenser  should  have  been  thoroughly  rinsed  with 


472   THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD. 

ammonia-free  water.  Collect  the  distillate,  50  c.c.  at  a  time, 
in  Nessler  tubes,  add  2  c.c.  of  Nessler's  reagent  to  each 
50  c.c,  and  determine  the  amount  of  ammonia  or  nitrogen 
in  each  as  follows  :  Place  in  another  Nessler  tube  50  c.c.  of 
ammonia-free  water  and  2  c.c.  of  Nessler's  reagent,  run 
in  from  a  burette  the  dilute  standard  ammonium  chloride 
solution  until  the  color  exactly  matches  that  of  the  first  50 
c.c.  of  the  distillate.  Repeat  the  process  for  each  50  c.c.  of 
distillate  until  the  test  shows  no  more  ammonia  is  coming 
over  from  the  retort.  The  total  amount  of  (dilute)  ammo- 
nium chloride  solution  used  indicates  the  total  amount  of 
nitrogen  of  the  /ree  ammonia.  Usually  all  the  free  am- 
monia will  come  over  in  the  first  150  or  200  c.c.  of  dis- 
tillate. Compare  the  colors  by  looking  down  through  the 
tubes  on  a  white  surface.  If  the  first  50  c.c.  give  a  pre- 
cipitate with  the  Nessler  reagent,  it  must  be  diluted  and 
the  amount  of  nitrogen  estimated  from  the  diluted  distil- 
late. The  free  ammonia  being  determined,  allow  the 
retort  to  cool  and  add  to  the  water  remaining  in  it  50 
c.c.  of  the  alkaline  permanganate  solution.  This  converts 
a  certain  proportion  of  the  nitrogenous  organic  matter  of 
the  water  into  ammonia ;  distil  as  before,  estimating  the 
amount  of  nitrogen  in  each  50  c.c.  of  the  distillate  until 
ammonia  ceases  to  come  over.  The  amount  of  ammo- 
nium cliloride  solution  thus  used  will  indicate  the  nitrogen 
of  albmninoid  ammonia,  and  the  total  amount  of  ammo- 
nium chloride  solution  used  in  the  whole  process  gives  the 
nitrogen  of  the  total  free  and  albuminoid  ammonia  in  1 
litre  of  water. 

The  importance  and  relative  value  of  the  results  of  the 
foregoing  tests  in  determining  tlie  ]mrity  or  safety  of  a 
drinking-water,  have  been  given  in  Chapter  V.  on  pages 
210  to  213,  inclusive. 


FOOD.  473 


Food. 


Milk. — Good  Milk.  —  Characteristics:  ivory  white, 
opaque,  neutral  or  slightly  alkaline  reaction,  no  sediment, 
no  unusual  or  offensive  taste  or  odor,  specific  gravity  1029 
or  above ;  cream,  10  to  40  per  cent,  by  volume ;  fats,  3 
per  cent,  or  more ;  total  solids,  12,5  per  cent,  or  more. 

Water  is  indicated  by  low  specific  gravity  and  by  low 
percentage  of  cream. 

Skimming  is  indicated  by  a  slightly  raised  specific 
gravity  (2°),  by  a  low  percentage  of  cream,  and  by  a 
poor  color,  though  the  deterioration  in  color  may  be  dis- 
guised by  the  addition  of  annotto,  etc. 

Watering  and  skimming  are  indicated  by  lowered  specific 
gravity,  by  low  percentage  of  cream,  and  by  poor  color. 

The  specific  gravity  is  determined  by  the  lactometer, 
in  using  which  correction  must  be  made  for  temperature, 
provided  the  latter  varies  much  from  60°  F.,  the  standard. 

The  percentage  of  cream  is  determined  by  the  cream 
gauge  or  creamometer ;  the  milk  should  be  allowed  to 
stand  in  the  creamometer  for  at  least  eight  to  ten  hours, 
and  should  be  covered. 

A  very  high  percentage  of  cream  tends  to  lower  the 
specific  gravity  theoretically  ;  but  when  a  milk  is  rich  in 
fat  it  is  also  rich  in  solids  not  fat. 

An  acid  reaction,  unless  very  slight,  indicates  souring 
of  the  milk  or  the  addition  of  some  preserving  acid.  A 
strongly  alkaline  reaction  indicates  the  addition  of  some 
substance  like  chalk,  sodium  carbonate,  etc.,  to  increase 
the  specific  gravity.  Such  addition  is  verified  by  an  ex- 
cess of  total  solids,  and  by  the  eifervescence  of  the  latter 
— after  drying — upon  the  addition  of  a  drop  or  two  of 
hydrochloric  acid. 


474  THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD. 

To  determine  the  percentage  of  total  solids:  Weigh  a 
small  evaporating  dish,  preferably  platinum,  add  5  to  10 
c.c.  of  milk,  and  weigh  dish  and  milk  to  get  weight  of 
milk ;  evaporate  to  dryness  over  a  water-bath,  completing 
the  drying  in  a  water-oven  until  there  is  no  further  loss 
of  weight ;  weigh  dish  and  contents  (total  solids) ;  sub- 
tract weight  of  dish,  multiply  by  100,  and  divide  by 
weight  of  milk.     Result :  the  percentage  of  total  solids. 

To  determine  the  p)crcentage  of  ash :  Ignite  the  total 
solids  over  a  naked  flame  until  all  black  specks  have 
disappeared ;  cool  and  weigh  ;  multiply  weight  of  ash  by 
100,  and  divide  by  weight  of  milk.  Result:  percentage 
of  ash. 

To  determine  the  percentage  of  fats :  Proceed  as  above 
with  10  c.c.  of  milk,  and  evaporate  until  the  residue  is  a 
tenacious  pulp,  extinguish  the  flame,  fill  the  dish  half- 
full  of  ether,  stir  and  triturate  the  residue  thoroughly  with 
a  glass  rod,  decant  the  ether  and  filter  it  through  a  small 
filter-paper,  reserving  the  filtrate ;  add  more  ether  to  the 
residue,  stir  and  triturate  as  before,  and  filter,  repeating 
the  process  three  times  or  till  the  residue  is  perfectly 
white ;  wash  the  filter-paper  well  with  ether,  collect  the 
latter  and  add  to  the  preceding  filtrate ;  evaporate  the 
ether  filtrate  until  only  the  fat  remains  and  its  weight  is 
constant ;  weigh  the  fat,  multiply  l)y  100,  and  divide  by 
the  weight  of  the  milk.     Result :  percentage  of  fat. 

This  method  when  carefully  performed  is  said  to  be 
fully  as  accurate  as  the  extraction  (Soxhlet)  method,  and 
does  not  require  the  more  expensive  apparatus  of  the 
latt(!r.  If  the  residue  from  which  tlie  fat  lias  been  ex- 
hausted is  carefully  dried  on  a  water-bath  at  100°  C. 
nntil  thoi'o  is  no  further  loss  by  evaporation,  its  weight 
will  be  that  of  the  "solids  not  fat"  of  the  milk. 


TESTS  FOB  MILK. 


475 


Centrifugal  method:  Where  a  centrifuge  is  available  for 
use    llie  following  metliod  for  the  fat-determination  will 


Fig.  92. 


^^ 


il 


Bottle  for  determining  percentage  of  fat  by  means  of  the  centrifuge. 

be  found  to  give  results  that  are  probably  accurate  to 
within  0.2  per  cent,  of  fat : 

Two  solutions  are  necessary  :    1 .    Fusel  oil,  37   c.c. ; 


476   THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD. 


Fig.  93. 


wood  or  methyl  alcohol,   13   c.c. ;  hydrochloric  acid,  50 

c.c.     2.  Sulphuric  acid,  sp.  gr.  1.83. 

Into  the  milk  bottle  (Fig.  92),  Avhich  is 
made  to  fit  the  centrifuge  and  Avhich  has  a 
long,  graduated  neck,  5  c.c.  of  the  milk  to  be 
examined  are  introduced  by  means  of  a  pip- 
ette, and  to  this  1  c.c.  of  the  alcohol  solution 
(1)  is  added  and  the  mixture  well  shaken  by 
hand.  The  sulphuric  acid  is  then  added, 
little  by  little,  Avith  frequent  shaking,  until 
the  bottle  is  filled  to  the  topmost  (zero)  grad- 
uation. It  is  then  rapidly  whirled  in  the 
centrifuge  until  only  the  fatoccu  pies  the  neck 
as  a  clear  layer,  when  the  actual  percentage 
can  be  read  from  the  graduations.  AVhen  the 
milk  is  very  rich — i.  e.,  containing  more  than 
5  per  cent,  of  fat — it  will  be  necessary  to  di- 
lute the  millv  with  an  equal  volume  of  Avater, 
and  then  to  multiply  tlie  result  by  2.  Like- 
Avise,  cream  should  be  diluted  Avith  4  parts  of 
Avater  and  the  result  multiplied  by  5.  The 
same  principle  is  employed  in  the  Babcock 
and  other  cream-testers  now  largely  used  by 
dairymen,  etc. 

A  somewhat  simpler  method  has  been  de- 
vised l)y  Prof  INIccker,  in  Avhich  the  only  re- 
agent is  sul])huric  acid,  sp.  gr.  1.83,  and  a 
tube  of  different  form  (Fig.  93)  is  used.  Into 
this  tube  the  milk  is  introduced  from  a  pipette 
holding  exactly  8.8  c.c,  and  having  a  long 
deliA^ery  end  to  carry  the  milk  beyond  the 
constricted  and  graduated  portion.  The  sul- 
phuric acid  is  then  added  in  equal  volume, 


TESTS  FOB  FAT  IN  MILK.  477 

filling  the  tube  to  the  zero  mark,  after  which  the  stopper 
is  inserted  and  the  milk  and  acid  thoroughly  mixed  by 
inverting  and  reinverting  the  tube.  This  breaks  up  the 
casein  of  the  milk  and  frees  the  fat,  which  will  collect  in 
the  graduated  part  when  the  tube  is  whirled  in  the  centri- 
fuge. Owing  to  cooling,  there  may  be  a  slight  contrac- 
tion of  the  liquid,  so  that  the  top  may  be  slightly  below 
the  zero  mark,  but  the  percentage  of  fat  is  indicated  by  the 
difference  of  the  reading  of  its  upper  and  lower  limits. 
On  this  account  it  is  well  to  again  warm  the  milk  by  im- 
mersing the  tube  in  hot  water,  and  to  give  a  second 
whirling  for  but  a  moment  or  two. 

Tlie  extraction  method:^  "About  10  grammes  of  milk 
are  carefully  weighed  in  a  glass  or  porcelain  capsule  and 
mixed  with  about  10  grammes  of  freshly  ignited  sand, 
pumice-stone,  or  asbestos,  and  evaporated  to  dryness  on  a 
water-bath.  The  dish  with  its  contents  is  then  finely 
pulverized  and  transferred  to  a  Soxhlet  extraction  appa- 
ratus and  the  fat  extracted  with  ether  for  at  least  five 
hours.  The  ether  extract  of  the  fat  is  then  evaporated  to 
dryness  on  a  water-bath  and  the  residue  dried  to  constant 
weight  (at  100°  C.)  and  weighed.  The  increased  weight 
of  the  flask  (of  the  Soxhlet  apparatus)  will  represent  the 
fat  in  the  10  grammes  of  milk." 

A  Soxhlet  apparatus  is  so  constructed  that  a  quantity 
of  ether  is  repeatedly  evaporated  and  condensed  in  it 
without  loss,  the  condensed  ether  being  made  to  percolate 
through  substances  placed  in  the  upper  part  of  the  appa- 
ratus and  to  extract  therefrom  soluble  matters,  such  as  fat, 
which  are  collected  in  a  small  flask  below,  and  from 
which  the  ether  can  finally  be  evaporated. 

Test  for  annotto :  A  percentage  of  cream  considerably 
lower  than  the  color  of  the  milk  would  indicate  justifies 
1  Bergey's  Handbook  of  Practical  Hygiene,  p.  129. 


478  THE  EXAMINATION  OF  A  IE,   WATEE,  AND  FOOD. 

tlie  suspicion  that  some  coloring-matter  has  been  used. 
Tliis  is  frequently  annotto. 

Coagulate  one  ounce  of  milk  with  a  few  drops  of  acetic 
acid  and  heat ;  strain,  and  press  out  the  excess  of  liquid 
from  the  curd ;  triturate  the  curd  in  a  mortar  or  dish  with 
ether,  decant  the  ether  and  add  to  it  10  c.c.  of  a  1  per  cent, 
solution  of  caustic  soda ;  shake,  and  allow  to  separate ; 
pour  oif  the  upper  layer  into  a  porcelain  dish,  put  in  two 
small  disks  or  strips  of  filter-paper ;  evaporate  gently  : 
annotto  will  dye  the  disks  an  orange  or  buff  color. 
Moisten  one  disk  with  dilute  solution  of  sodium  carbonate 
to  fix  the  color ;  touch  the  other  disk  with  a  drop  of  stan- 
nous chloride  :  annotto  will  give  a  rich  pink  color.  This 
test  is  sensitive  to  1  part  of  annotto  in  1000  of  milk,  and 
with  milk  in  any  condition. 

Test  for  horic  acid:  Upon  igniting  the  total  solids, 
boric  acid  or  boron  gives  a  greenish  tinge  to  flame. 
Place  in  a  porcelain  dish  5  c.c.  of  milk,  1  drop  of 
strong  hydrochloric  acid,  and  2  drops  of  a  saturated 
tincture  of  turmeric.  Dry  on  a  water-bath,  remove  as 
soon  as  dry ;  cool,  and  add  1  drop  of  ammonia  on  a 
glass  rod.  A  slaty-blue  color,  changing  to  green,  is  given 
if  borax  is  present.  This  test  will  show  y-oVo  gi"S"i  of 
borax.     Less  will  give  the  green  color,  but  not  the  bine. 

Ted  for  salicylic  acid  and  salicylates  (Bergey) :  Dilute 
the  milk  (100  c.c.)  with  an  equal  bulk  of  distilled  water 
at  ()0°  C. ;  precipitate  with  8  drops  of  acetic  acid  and  8 
drops  of  a  solution  of  mercuric  oxide  in  nitric  acid  ;  shake 
and  filter.  To  the  filtrate  add  50  c.c.  of  ether,  which 
lakes  up  tlie  salicylic  acid  ;  decant,  and  filter  the  super- 
natant ether.  Evaporate  this  filtrate  nearly  to  dryness, 
and  add  a  few  drops  of  highly  diluted  neutral  ferric 
cliloride.  A  violet  color  indicates  the  presence  of  salicylic 
acid,  the  depth  of  color  increasing  with  the  amount. 


TEST  FOR  FORMALDEHYDE.  479 

To  test  for  salicylic  acid  in  butter,  it  is  first  treated 
with  sodium  carbonate  and  the  homogeneous  mixture 
acidulated  with  sulphuric  acid,  and  then  shaken  with  a 
mixture  of  equal  parts  of  ether  and  petroleum  ether,  after 
which  the  supernatant  ether  is  filtered  off  and  treated  as 
above. 

Test  for  formaldehyde  (Bergey) :  Add  an  equal  volume 
of  water  to  the  milk  or  butter  to  be  tested,  place  in  a  flask 
on  a  steam-bath  and  distil  over  about  one-fourth  the  total 
volume.  Treat  10  c.c.  of  the  distillate  with  2  drops 
of  ammoniacal  silver  solution  (made  by  dissolving  1 
gramme  of  silver  nitrate  in  30  c.c.  of  distilled  water 
and  adding  ammonia  until  the  precipitate  that  first  ap- 
pears is  redissolved,  then  diluting  to  50  c.c.  with 
water).  If  formaldehyde  is  present,  it  causes  a  black  cloud 
in  the  distillate  after  standing  for  several  hours  in  the  dark. 

Harrington  gives  the  following  test  among  others :  "Mix 
in  a  porcelain  dish  10  c.c.  each  of  milk  and  hydrochloric 
acid  (sp.  gr.  1.2)  and  1  drop  of  ferric  chloride  solution. 
Heat  and  stir  vigorously.  If  formalin  has  been  added,  a 
violet  color  will  appear  before  the  boiling-point  has  been 
reached,  varying  in  intensity  according  to  the  amount 
present.  This  process  is  exceedingly  delicate  and  will 
detect  1  part  in  500,000  in  the  fresh  condition."  ^ 

According  to  Hehner,  "no  formaldehyde  could  be  de- 
tected at  the  end  of  a  week  in  a  sample  (of  milk)  to  which 
had  been  added  1  part  in  100,000 ;  after  two  weeks  none 
could  be  detected  in  a  sample  of  1  })art  in  50,000 ;  and 
after  three  weeks  only  a  faint  trace  could  be  detected  in  a 
sample  of  1  part  in  25,000."  ^ 

Butter  and  Oleomargarine. — Pure  butter  should  have 
good  taste,  odor,  and  color ;  it  should  not  be  rancid,  and 

1  For  other  tests  for  formaldehyde,  see  Harrington,  pp.  108,  109,  and 
Leflfmann  and  Bevan's  Food  Analysis,  pp.  220-222. 
^  Leflfmann  and  Bevan,  loc.  cit. 


480   THE  EXAMINATION   OF  AIR,   WATER,  AND  FOOD. 

should  not  contain  too  much  water  or  salt,  nor  should  it 
have  any  added  coloring-matter.  The  average  composi- 
tion should  be  about  as  follows  :  fat,  82  per  cent. ;  casein, 
2  per  cent,  (not  over  3  per  cent.) ;  ash  or  salts,  2  per 
cent.;  water,  13  per  cent.  Butter  fat  is  a  compound  of 
glycerin  with  certain  fatty  acids,  some  of  them  volatile 
and  soluble  in  hot  water,  others  non-volatile  and  insoluble 
in  hot  water. 

Oleomargarine  consists  of  ordinary  animal  or  vegetable 
fats,  melted,  strained,  cooled  with  ice,  worked  up  with 
milk,  colored,  and  salted.  The  fats  are  usually  beef  or 
mutton  fat,  lard,  or  cotton-seed,  palm,  or  cocoanut  oil.  If 
care  and  cleanliness  are  observed  in  the  manufacture,  oleo- 
margarine is  not  harmful  or  innutritions,  but  it  should  not 
be  sold  as  butter. 

Fraud  is  to  be  detected  by  observing  the  differ- 
ence in  composition  and  properties  of  the  ffds.  For 
instance  : 

BuTTEE  Fat.  Beef  Fat,  etc. 

1.  The  specific  gravity  is  very  1.  Beef  fat,  etc.,  is  never  above 
rarely  below  910,  never  below  909.8.  904.5. 

2.  The  soluble,  volatile  fatty  2.  Earely  more  than  i  per  cent., 
acids  average  between  6  and  7  per  never  above  i  per  cent. 

cent.,  never  below  4.5  per  cent. 

3.  The  insoluble  fatty  acids  form  3.  Generally  about  95  per  cent. 
about  88   per   cent,    of    the    total 

weight  of  butter  fat. 

4.  The  melting-point  of  the  fat  4.  Earely,  if  ever,  above  82°  F. 
varies  from  h6°  to  94°  F. ;  is  usu- 
ally from  88°  to  90°  F. 

5.  Is  readily  and  completely  solu-  5.  Less  so  and  leaves  a  residue, 
ble  in  ether. 

6.  Under  the  microscope  pure  6.  The  contours  of  the  small  oil 
butter  fat  consists  of  a  collection  globules  are  less  distinct,  and  the 
of  small  oil  globules,  with  an  oc-  larger  oues  are  more  numerous  aud 
casional  large  one.  irregular  in  size. 

7.  No  crystals,  except  when  the  7.  Crystals  of  the  non-volatile 
fat  ha-s  been  melted.  acids  are  often  seen. 


TESTS  FOE  BUTTER  AND   OLEOMARGARINE.   481 

To  determine  the  sjiecijic  gravity  of  butter  fat :  Melt 
a  quantity  of  the  butter  in  a  beaker  in  a  water-bath  at 
about  150°  F.  When  the  fat  is  perfectly  clear  and  trans- 
parent, carefully  decant  the  fat  from  the  lower  stratum 
of  water,  curd,  and  salt  into  a  fine  filter ;  collect  the 
filtrate  and  pour  into  a  specific  gravity  bottle,  which  has 
been  previously  weighed,  both  when  empty  and  when 
filled  with  distilled  water  at  100°  F.  See  that  the  bottle 
is  exactly  full  of  the  fat,  wipe  clean,  and  weigh  when  the 
temperature  is  as  near  100°  F.  as  possible,  because  solidi- 
fication soon  begins  below  this  temperature.  Subtract  the 
weight  of  the  bottle,  divide  by  the  weight  of  the  water 
which  the  bottle  contains,  and  multiply  by  1000 ;  the 
result  is  the  specific  gravity. 

To  find  the  melting-point :  Pour  a  little  melted  fat  into 
a  small  test-tube  (2"  X  I")  and  cool.  Partly  fill  two 
beakers  of  unequal  size  with  cold  water ;  place  the  test- 
tube  in  the  smaller  (taking  care  to  allow  no  water  to  mix 
with  the  fat),  and  the  smaller  in  the  larger,  and  gently 
heat  the  outer  beaker.  Suspend  a  thermometer  in  the 
smaller,  near  the  test-tube,  and  note  the  temperature  when 
the  fat  begins  to  melt ;  this  is  the  melting-point. 

To  determine  the  percentage  of  insoluble  {non-volatile) 
fatty  acids:  To  6  grammes  of  butter  fat  add  50  c.c.  of 
alcohol  containing  2  grammes  of  caustic  potash  (KHO) 
and  boil  gently  for  fifteen  or  twenty  minutes  to  saponify 
the  fat.  Dissolve  the  soaps  thus  formed  in  150  to  200 
c.c.  of  water,  and  decompose  with  about  25  c.c.  of  dilute 
hydrochloric  acid.  The  separated  fatty  acids  are  poured 
upon  a  weighed  filter-paper,  washed  with  2  litres  of 
boiling  water,  dried  at  95°  to  98°  C  and  then  weighed. 
The  weight  of  these  insoluble  fatty  acids  should  not  be 
over  90  per  cent,  of  the  weight  of  the  butter  fat. 

31 


482    THE  EXAMINATION  OF   WATER,  AIR,  AND  FOOT). 

Flour  and  Bread. —  Wheat  Flour. — Characteristics  : 
almost  perfectly  white,  smooth  and  free  from  grit ;  no 
mouldy  or  unpleasant  odor ;  cohesive  when  lightly  com- 
pressed ;  no  signs  of  parasites  under  the  microscope  ;  water 
less  than  18  per  cent.;  ash  less  than  2  per  cent. 

"  The  roller  process  yields  a  slightly  rough  flour,  and 
the  hard  winter  wheat  may  give  a  yellowish  tinge.  Good 
flour  is  slightly  acid  to  test-paper,  but  not  to  the  taste,  and 
an  acidity  that  may  be  recognized  by  the  senses  means  a 
change.  Acid  flour  means  sour  bread,  and  any  disagree- 
able taste  or  odor  indicates  bad  flour.  When  boiling 
water  is  poured  on  a  little  flour,  there  should  arise  no 
odor  but  that  of  freshly  ground  wheat."  ^ 

To  determine  the  percentage  of  water  and  ash :  In  a 
weighed  platinum  (or  porcelain)  dish  place  about  50 
grammes  of  flour,  weigh,  and  dry  over  a  water-bath  for 
an  hour  or  so  ;  then  complete  the  evaporation  in  a  water- 
oven  until  there  is  no  further  loss  of  weight ;  weigh,  sub- 
tract this  weight,  less  the  weight  of  the  dish,  from  the 
original  weight  of  the  flour.  Multiply  the  remainder  by 
100  and  divide  by  the  original  w^eight  of  the  flour.  The 
result  is  the  percentage  of  water.  Then  ignite  the  dried 
flour  in  the  dish  and  incinerate  till  there  are  no  longer 
any  black  particles  and  only  the  ash  remains  ;  cool,  weigh, 
subtract  weight  of  dish,  multiply  the  remainder  by  TOO, 
and  divide  by  the  original  weight  of  the  flour.  The 
result  is  the  percentage  of  ash. 

To  determine  the  jyei^centage  of  gluten :  By  means  of  a 
glass  rod  mix  a  weighed  quantity  of  flour  with  a  little  dis- 
tilled water  into  a  stiff  dough  ;  then  repeatedly  wash  away 
the  starch  and   soluble  constituents,  kneading  the  dough 

^  Colonel  A.  A.  WooclhnlJ.  M.  D.,  article  on  "Military  Hygiene,"  in 
The  Reference  Handbook  of  the  Medical  Sciences. 


TESTS  FOR  FLOUR  AND  BREAD.  483 

with  the  rod  or  fingers,  and  continuing  until  the  wash- 
water  comes  away  clear ;  the  gluten  and  a  small  amount 
of  fat  and  salt  remain.  Spread  on  a  weighed  dish  or 
crucible  lid,  dry  in  a  water-oven,  and  weigh ;  multiply  by 
100  and  divide  by  the  original  weight  of  the  flour.  The 
result  is  the  approximate  percentage  of  gluten.  The  gluten 
should  pull  out  into  long  threads ;  otherwise,  it  is  poor. 

"The  relative  strength  and  elasticity  of  the  gluten,  which 
are  determined  comparatively  by  manipulating  a  small 
quantity  of  flour  intimately  mixed  with  half  its  weight 
of  water,  make  a  standard  for  comparison.  This  is  known 
as  the  dough-test,  and  its  failure  shows  weak  flour,  from 
poor  wheat  or  imperfect  milling  and  defective  gluten."  ^ 

An  excess  of  water  impairs  the  keeping  quality  and 
lessens  the  amount  of  nutriment  in  the  flour.  An  excess 
of  ash  indicates  the  addition  of  mineral  substances.  A 
deficiency  of  gluten  may  also  indicate  that  the  flour  is 
not  pure  wheat  flour.  Parasites  and  fungi  are  especially 
likely  to  be  found  in  old,  damp,  or  inferior  flour. 

To  test  for  mineral  substances :  Shake  a  little  flour  in  a 
test-tube  with  some  chloroform,  and  allow  it  to  stand  for 
a  few  minutes.  The  flour  floats  and  any  mineral  matter 
sinks  to  the  bottom,  when  it  can  be  removed  with  a 
pipette  and  examined  under  a  microscope. 

Wheat  Bread. — Characteristics  :  fairly  dry,  light,  and 
spongy ;  clean  and  nearly  white  ;  of  pleasant  taste  ;  not 
sodden,  acid,  or  musty  ;  ash  not  over  3  per  cent.;  no  para- 
sites or  mouldiness  ;  no  flour  other  than  wheat ;  but  little, 
if  any,  alum  ;  no  copper  sulphate. 

Test  for  alum:  Add  5  c.c.  of  a  5  per  cent,  tincture  of 
logwood  and  5  c.c.  of  a  1 5  per  cent,  solution  of  ammonium 
carbonate  to  25  c.c.  of  water ;  soak  a  crumb  of  the  bread 
1  Colonel  A.  A.  Woodhull,  M.  D.,  loc.  cit. 


484   THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD. 

in  this  for  a  few  minutes ;  drain  and  gently  dry  :  alum 
is  indicated  by  a  violet  or  lavender  color ;  its  absence  by 
a  dirty-brown  color  on  drying. 

Test  for  copper  sulphate:  Draw  a  glass  rod  that  has 
been  dipped  in  a  solution  of  potassium  ferrocyanide  across 
a  cut  slice  of  the  bread  :  copper  is  indicated  by  a  brown- 
ish-red streak. 

Test  for  ergot  in  flour  or  bread  :  Add  liquor  potassse  ; 
a  distinct  herring-like  odor  (due  to  propylamine)  is  appre- 
ciable if  ergot  be  present. 

An  excess  of  water,  an  unnatural  whiteness,  and  a  low 
percentage  of  ash  in  bread  indicate  the  addition  of  rice. 
Potatoes  give  an  increased  percentage  of  water  and  an 
alkaline  ash. 

For  further  tests  and  details  in  work  pertaining  to  a  laboratory  of 
hygiene  the  reader  is  referred  to  Fox's  Examination  of  Food,  Air,  and 
Water ;  Kenwood's  Hygienic  Laboratory  ;  Bergey's  Handbook  of  Prac- 
tical Hygiene ;  Harrington'  s  Practical  Hygiene ;  and  Leffniann  and 
Bevan's  Food  Analysis. 


INDEX. 


Absorption  of  foods,  233 
Accessory  foods,  244 
Acetylene  gas,  88 
Adulterants    and    preservatives, 

266 
Adulteration  of  foods,  267 
Air,  70 

bacteria  in,  76 

collection  of,  459 
currents,  determination  of  ve- 
locity of,  114 
direction  of,  118-121 
diseases  caused  by  impure,  93 
distribution  of,  116 
examination  of,  459 
filtration  of,  110 
purification  by  fire,  104 
saturation  of,  81 
Air-propeller,  123 
Air-supply,  conduits  for,  110 

source  of,  110,  138 
Alcohol,  273 

indications.for  use  and  absten- 
tion, 273-276 
relation  of,  to  food,  273 
Alexins,  59 

Alum  in  bread,  test  for,  483 
use  of,  in  purifying  water,  185, 
190,  198 
Amboceptors,  Ehrlich's,  64 
Ammonia,      "albuminoid,"      in 
water,  218 
"free,"  in  water,  217 
in  air,  75 

test  for  free  and  albuminoid, 
471 
Amylopsin,  action  of,  232 


Anderson's  process  for  purifying 

water,  186 
Anemometer,  115 
Annotto,  test  for,  in  milk,  477 
Antimicrobin,  68 
Antiseptics,  330 
Antitoxins,  59 

methods  of  preparing,  64 

statistics  of  use  of,  67    • 

theory  of,  59 
Apparatus  for  lighting,  86 

for  steam  disinfecting,  335 
Aqueous  vapors,  74,  81 
Area  drained  by  wells,  162,  167 
Argon,  73 
Army  canteen,  441 

medical  officers,  duties  of,  424, 
442 

rations,  433-435 
Artesian-water,  151,  163 
Artesian-wells,  163 
Artificial  ventilation,  111,  122 
Ashes,  382 
Aspiration,  113 
Atavism,  286 
Atmosphere,  70 

composition  of,  70 

impurities  in,  75 

of  mines,  93 

of  ships,  93 

weight  of,  70 
Atmospheric  contamination,  ex- 
tent of,  105 

index  of,  105 
Autogenetic  diseases,  causes  of, 

31 

B. 
Bacilli,  40 
Bacillus,  the  colon,  in  water,  215 

485 


486 


INDEX. 


Backus  heater,  133 
Bacteria  as  an  index  of  purity  of 
filtered  water,  198 

atypical  forms  of,  40 

classification  of,  40,  41 

collection  of,  in  air,  459 

definition  of,  36 

differentiation  of,  46,  47 

discovery  of,  37 

in  air,  76 

involution  forms  of,  40 

isolation  of  different  species  of, 
42 

parasitic,  50 
in  sewer-gas,  89 

pathogenic,  50 

requirements  of,  38 

saprophytic,  49 
Bacterial  examination  of  air,  459 

of  water,  215 
Bacteriology,  36 
Barracks,   construction   and  ar- 
rangement of,  426 
Bathing,  295 

rules  for,  296 

sea-,  297 

time  of,  297 
Baths,  cold,  296 

Russian,  298 

Turkish,  298 

warm,  298 
Beans,  nutritive  value  of,  265 
Bedding,  disinfection  of,  354 
Beef,  256 

Beef-fat,  characteristics  of,  480 
Beef-tea  as  a  stimulant,  271 

whole,  recipe  for,  261 
Berkfeldt  filter,  208 
Beverages,  277 

carbon  dioxide  in,  278 

sanitary  precautions  concern- 
ing, 278 
Bichloride  of  mercury  as  a  disin- 
fectant, 339 
Bile,  action  of,  232,  233 
Biologic  action  in  soil,  158 
IMackboards,  school,  318 
Boiling,  disinfection  by,  356 
Boric  acid,  test  for,  in  milk,  478 
Bread,  263 

test  for  alum  in,  483 


Bread  test  for  copper  sulphate 
in,  484 
for  ergot  in,  484 
Broiling,  260 
Broths,  260 

Buchner,  humoral  theory  of,  59 
Burial  permits,  450 
Butter,  254 

examination  of,  479 
Butter-fat,  characteristics  of,  480 
Buttermilk,  248 

c. 

Calcium  hydrate,  341 
Camp  pollution,  429 
Camp-hospitals,  427,  439 
Camps  of  detention,  377 
diseases  of,  433 
disposal  of  excreta  in,  437 
location  t)f,  425 
of  probation,  377 
of  refuge,  377 
typhoid  fever  in,  428-432 
water-supply  of,  433 
Canteen,   army,   advantages   of, 

441 
Carbohydrates,  functions  of,  222, 
224,  238 
sources  of,  238 
Carbolic  acid  as  a  disinfectant, 

340 
Carbon  dioxide,  73 
effects  of,  78 
excretion  of,  79 
in  beverages,  278 
in  soil-air,  91 
normal  proportion  of,  73 
poisoning  by,  99 
Pettenkofer's  test  for,  462 
tests  for,  460 
monoxide  from  stoves,  130 

poisoning  by,  99 
proportion  of,  to  nitrogen  in 
diet,  236 
Carbonic  acid.     See  Carbon  di- 
oxide. 
Care  of  school-houses,  321 
Carpets,  etc.,  disinfection  of,  354 
Census,  the,  447 

reports,  U.  S.,  statistics  from, 
23 


INDEX. 


487 


Cereals,  262 

Cesspools,  dangers  of,  385 

disinfection  of,  385 
Cheese,  254 
Chemical  disinfectants,  338 

treatment  of  sewage,  411 
of  water,  184 
Chloride  of  zinc,  341 
Chlorides  in  water,  test  for,  464 
Chlorinated  lime,  338 

soda,  338 
Chlorine,  342 

or  chlorides  in  water,  217,  464 

test  for,  464_ 
Cisterns  for  rain-water,  154 
Clark's     process     for     purifying 

water,  184 
Cloak-rooms     in    school-houses, 

319 
Closets,  earth-,  386 

pail-,  385 

water-,  399 
Clothing,  299 

advantages  of  woollen,  300 

conveyance    of    infection    by, 
304 

disinfection  of,  353,  354 

influence  of,  upon  health,  303 

materials  used  for,  299 

of  soldiers,  436,  437 

purpose  of,  299 

relative  absorption  of  heat  by, 
304 

sophistication  of,  303 

tests  for  materials  for,  302 
Coal,  products  of  combustion  of, 

84 
Coal-gas,  composition  of,  100 

poisoning  by,  101 

products  of  combustion  of,  85, 
86 
Coffee,  271 

Cold  baths,  effects  of,  296 
Colony,  a  bacterial,  43 
Columbia  filters,  207 
Combustion  products,  84 

influence  upon  health  of,  98 
specific  gravity  of,  86 
Comparative    mortality    figure, 

455 
Condensed  rations,  434 


Condiments,  244 
Congenital  diseases,  286 
Consanguineous    marriages,    ob- 
jections to,  288 
Construction  and  care  of   wells, 
165 
of  school-houses,  318 
Contact  beds  for  sewage,  416 
Contagion,  nature  of,  52 
Contagious    diseases,    definition 
of,  31 
in  schools,  323-326 
Contamination    of    atmosphere, 

extent  of,  105 
Convected  heat,  127 
Cooking,  object  of,  234,  259 
of  vegetables,  265 
thoroughness  of,  234,  259 
Copper    sulphate,    test    for,    in 
bread,  484 
in  water,  470 
Corn,  262  _ 

Corrosive  sublimate  as  a  disin- 
fectant, 339 
Cotton  in  clothing,  301 
Cowls,  ventilating,  112,  113 
"Cramps,"  cause  of,  when  bath- 
ing, 296 
Cream,  digestibihty  of,  247 
Creohn,  341 
"Crowd  poison,"  82 

effects  of,  97 
Cubic  space  in  ventilation,  109 
Culture-media,    preparation    of, 
45 
reaction  of,  41 
temperature  of,  41 


Death-certificate,     standard, 

452 
Death-rates,  451,  455 

daily  or  weekly,  453 

of  cities,  453 

showing  sanitary  gain,  23 

standard,  455 

zymotic,  454 
Deep  water,  151,  163 

wells,  163 
Deodorants,  330 


488 


INDEX. 


Detention  at  ports  of  entry,  367 
camps  of,  377 

period  of,  in  quarantine,  367, 
374,  375 
Devices  for  ventilation,  116 
Dietetic  rules,  234 
Dietetics,  225 

aesthetic  factors  in,  225 
Differentiation  of  bacteria,  46,  47 
Diffusion,  111 
law  of,  72 
rate  of.  111 
Digestion,  hydrolysis  in,  227 
gastric,  230 
intestinal,  231,  232 
physiology  of,  226 
salivary,  228 
Diphtheria  antitoxin,  method  of 

preparing,  64 
Direct  radiation,  143 
Direct-indirect  radiation,  144 
Diseases  affecting  animals  used 
for  food,  258 
classification  of,  31 
congenital,  286 
definitions  of,  30,  31 

and  causes  of  autogenetic, 
31 
due  to  impure  air,  93 

to   impure    drinking-water, 

171-177 
to  respiratory  vitiation,  97 
incubation-periods  of,  325 
infectious,  in  schools,  323-326 
inherited,  285 

methods  of  combating,  286 
study  of,  443 

transmissible  by  heredity,  287 
Disinfectant,   definition   of,    329 
application  of,  in  quara!ntine 
work,  372 
Disinfectants,  chemical,  338,  361 
comparative  table  of,  352' 
gaseous,  337 
mechanical,  333 
physical,  356 
physiological,  333 
thermal,  333 
Disinfecting    apparatus,    steam, 

335  I 

Disinfection,  33,  329  I 


Disinfection  by  dry  heat,  337 

by  fire,  333 

by  formaldehyde,  345 

by  hot  water,  336,  356 

by  steam,  333 

efficacy  of,  331 

evidence  as  to,  332 

final,  of  rooms,  354 

in  the  sick-room,  353 

of  bedding,  354 

of  carpets,  etc.,  354 

of  cesspools,  385 

of  clotliing,  353,  354 

of  excreta,  339,  340,  352 

of  infectious  cases,  352 

of  rooms,  355 

of  school-houses,  320 

of  spores,  332 

of  vessels  in  quarantine,    371- 
374 

personal;  353 

Schering's  method  of,  347 

thoroughness  of,  331 

Trillat's  method  of,  346 
Disinfector,  duties  of  a,  330 
Distillation     of    drinking-water, 

200,  201 
Distribution  of  air,  116 
Domestic  purification  of  water 

198 
Drinking-water,    distillation    of, 
200,  201 

examination  of,  213 

infection  by,  168 
necessity  for  boiling,  208 
Drip-safes,  398 

Dry  heat,  disinfection  by,  337 
Duration  of  hfe,  mean,  456 
probable,  456 
of  school-work,  311,  312 
Dust,  influence  of,  in  air,  94,  95 
Duties  of  army  medical  officers, 

424,  442 
Duty  of  physicians,  27 

E. 

Earth-closets,  386 
Economy  in  heating,  127 
Eggs,  value  of,  as  a'food,  255 
Ehrlich's  lateral  chain  theory,  62 


INDEX. 


489 


Ejector  sewerage  system,  384 
Environment,  influence  of,  34 
on     predisposed     constitu- 
tions, 286 
Enzymes,  action  of,  226 
cliaracteristics  of,  227 
digestive,  226 
of  vegetable  origin,  235 
Ergot,  test  for,  in  bread,  484 
Estimation  of  radiating  surfaces. 

146 
Examination  of  air,  459 
of  butter,  480 
of  drinking-water,  213,  464 
of  flour,  482 
of  food,  473 
of  milk,  473 
Excreta,  disinfection  of,  339,  340 
disposal  of,  in  camps,  437-439 
Exercise,  289 

amount  necessary,  294 
effect  upon  brain  development, 
293 
upon     digestive     functions, 

293 
upon  excretion,  291 
upon  heart  and  circulation, 

292 
upon  heat-production,  292 
upon  muscles,  290 
upon  respiratory  organs  and 
functions,  290 
importance  of,  289 
Exhaust  system,  124 
Exhauetion  theory  of  Pasteur,  58 
Expectant  attention,  danger  of, 
280  '         t,  , 

Expectation  of  life,  456 
External  ventilation,  103 


Factors  of  ventilation,  105 

Fans,  ventilating,  122,  123 

Farr,  Dr.  Wm.,  20 

Fatigue,  causes  of,  294 

Fats,   constructive   property  of 
240,  241 
digestibility  of,  242 
functions  of,  222,  224,  240 
properties      of     butter-     and 
beef-,  480 


Fats,  sources  of,  239 

to  determine  specific  gravity 
of,  481 
melting  point  of  butter-,  481 
Fatty  acids,  to  determine  insol- 
uble or  non-volatile,  481 
Filter-beds,  plan  of,  188 
Filters,  action  of  sand-,  188 
cleansing  of  sand-,  197 
construction  of  sand-,  191 
functions  of  sediment  layer  in, 

189 
house-,  203 

material  used  in  sand-,  193 
Filtration,  187 
of  air,  110 
of  rain-water,  153 
of  sewage,  411 
rate  of,  197 

regulation  of,  191 
Fire,  disinfection  by,  333 
Fish,  257  . 
Fixtures,  location  of  house-,  392 

traps  of  house-,  392 
Flies  as  carriers  of  infection,  430 
Floor-space  in  ventilation,  109 
Flour,  characteristics  of  wheat- 
482 
test  for  minerals  in,  483 
to  determine  the  ash  in,  482 
gluten  in,  482 
water  in,  482 
Flues,  hot-air,  size  of,  139 
Flush  tank,  Field's  siphon,  408 
Food,  221 

amount  necessary  for  life  and 

health,  235 
cooking  of,  234 
definition  of,  221 
functions  of,  221 
of  the  soldier,  433-435 
Food-principles,  classification  of, 
222 
properties  of,  224 
use  of,  222 
Food-relationship  in  diet,  236 
Food-salts,  function  of,  243 

sources  of,  243 
Foods,  absorption  of,  233 
accessory,  244 
adulteration  of,  267 


490 


INDEX. 


Foods,  relative  value  of,  269 

use  of  preservatives  in,  267 
Forbes  sterilizer,  201 

advantages  of,  202 
Forces  of  ventilation.  111 
Formaldehyde,  345,  358 

as  a  deodorant,  351 

disinfection  by,  345 

methods  of  using,  346 

production    from    methyl    al- 
cohol, 347 

regenerators     for     vaporizing, 
348,  349 

solutions  of,  345 

test  for,  in  milk,  479 

with  permanganate  of  potash, 
351 
Formalin,  345 
Formic  aldehyde,  345 
Formula  for  problems  in  ventila- 
tion, 108 
Free  pratique,  375 
Fruits,  266 
Frying,  261 
Fumigation,  355,  357 
Furnaces,  hot-air,  136 
Furs,  301 

G. 

Garbage,  disposal  of,  382 
Gaseous  impurities,  77 
Gas-.stoves  and  grates,  131 
Gastric  digestion,  230 
Germ  theorj"^,  37,  50 

arguments  for,  52 
Germicides,  329 
Gluten,  to  determine  percentage 

of.  482 
Glycogen.  238 

Graphic  charts  of  statistics,  447 
Grate  fires,  open,  128 
Grates,  ventilating,  128,  129 
Grease  trap,  395 
Grinding  grain,  effect  of,  262 
Ground-water,  151,  157 

current  of,  160 

purification  of,  158 


Hard  water,  154 
Hardne.ss  of  water,  154,  219 


Hardness  of  water,  permanent. 
154 
temporary.  154 
test  for.  468 
Headache  in  school  children,  314 
j  Health,  definition  of,  30 
I      of  soldiers,  422-427 
j  Heat,  air-movement  due  to,  113 
I      converted.  127 

distribution  of.  136,  141 
radiant,  126 

relative   absorption  by  cloth- 
ing, 304 
transmission  of,  141 
Heating  by  hot  air,  136 
by  hot  water,  142 
bv  steam,  143 
Heredity,  definition  of,  282 
importance  of  observing  laws 
of,  283 
Hippocrates,    hvgienic   rules  of, 

19 
Hospital  ships,  440 

tent,  the  Mxmson,  440 
Hospitals,  impurity  of  air  in,  108 

military,  427,  439 
Hot-air  flues,  shape  of,   138 
size  of,  139 
furnaces,  136 

air-supply  of,  138 
combu.stion  of  fuel  in,  139 
limitations  of,  141 
location  of,  138 
requirements  of,  136,  137 
Hot  water,  disinfection  by,  336, 
356 
heating,  141 
House  drainage,  387 
House-drains,  388 
air  inlets  to,  391 

connection   of,   with  sewer, 
390 
with  soil-pipes,  390 
con.struction  of,  390 
quarantine,  378 
House-filters.  203 
ela.s.sification  of.  205 
dangers  of,  204 
materials  for,  208-212 
requisites  of,  204 
self-cleaning  devices  for,  208 


INDEX. 


491 


House-fixtures,  connection  of,  to 

waste-pipes,  392 
House-warming,  126 
Human   exhalations,    effects   of, 

97 
Humidifier,  141 
Humidity  of  warmed  air,   139- 

141 
Humoral  theory,  59 
Hydrocarbon  lamps,  87 
Hydrocyanic  acid  as  an  insecti- 
cide, 344 
Hydrogen  dioxide  as  a  disinfec- 
tant, 342 

peroxide  as  a  disinfectant,  342 

sulphide,  symptoms  due  to  in- 
halation of,  101 
Hygiene,  ancient,  20 

definition  of,  17 

development  of,  as  a  science, 
20 

military,  422 

order  of  stvidy  of,  26 

personal,  279 

progress  in,  21-24 

reasons  for  study  of,  27-29 

school,  310 

scope  of,  17-19 


Ice-water,  abuse  of,  212 

purity  of,  212 
Illuminating  agents,  influence  of, 

86 
Illuminating-gas,  composition  of, 
100 

poisoning  by,  100 
Illumination,  apparatus  for,  87 

influence  on  health  of,  86 
Immunity,  theories  of,  57-64 
Impure  air,  diseases  due  to,  93 

water,  diseases  due  to,  171,  177 
Impurities   due   to   combustion, 
84 

due  to  respiration,  etc.,  77,  78 

gaseous,  77 

in  air,  75 

mortality  due  to,  95 
Impurity  of  air  in  hospitals,  108 
Incubation,  period  of,  56 


Incubation-period   of   infectious 

diseases,  325 
Index  of  atmospheric  contamina- 
tion, 105 
Indirect  radiation,  143 
Infant  mortality,  causes  of,  454 

rate  of,  454 
Infection  by  drinking-water,  173 

conveyance    of,    by    clothing, 
304 

by  oysters  and  clams,  257 
Infectious  diseases,  causes  of,  31 
disinfection  of  cases  of,  352 
Inherited  diseases,  285 
Inland  quarantine,  376 
Inlets,  fresh-air,  to  house  drains, 
391 

ventilation,  location  of,  120 
size  of,  120 
Inoculation,  51 
Inspection,  quarantine,  367 
Intermittent  filtration  of  sewage, 

393 
Internal  ventilation,  104 
Intestinal  digestion,  231,  232 
Involution-forms,    causation   of, 

40 
Iron,  effect  of,  in  water,  172 

sulphate,  342 

test  for,  in  water,  470 
Irrigation  treatment  of  sewage, 

413 

K. 

Kefir,  248 
Koch's  postulates,  54 
Koumiss,  248 
Kresols,  340 

Kuhn   formaldehyde   generator, 
348,  350 

L. 

Labarraque's  solution,  338 

Lake-water,  157 

Lateral  chain  theory  of  immun- 
ity, 62 

Lead  in  water,  173 
test  for,  470 

Leather,  301 

Leguminous  plants,   food   value 
of,  265 


492 


INDEX. 


Level  of  ground-water.  159 
Life-table,  factors  of,  457 
Life-tables,  value  of,  457 
Light,  305 

germicidal  effect  of,  306 
importance  of  an  abundance 

of,  307 
influence  of,  upon  health,  305 

upon  metabolism,  307 
penetration  of  sun-,  306 
therapeutic  effects  of  sun-,  307 
Lighting  agents,  influence  of,  86 
increased  by  prismatic  devices, 

308 
of  school  rooms,  311 
Lime,  chloride  of,  as  a  disinfec- 
tant, 338 
chlorinated,  as  a  disinfectant, 

338 
milk  of,  as  a  disinfectant,  341 
Linen  in  clothing,  301 
Location  of  school-houses,  320 
of  ventilation  inlets,  120 

outlets,  118 
of  wells,  161,  166 
Loomis-Manning  filters,  209,  210 
Lysins,  64 

M. 

Malaria  and  typhoid  fever,  433 

Marriage,  284 

proper  age  for,  284 

Marriages,  objections  to  consan- 
guineous, 288 

Mastication,  value  of,  229,  234 

Mean  after-lifetime,  456 
age  at  death,  456 
duration  of  life,  456 

Meat,  characteristics  of  good,  256 
composition  of,  256 

Meats,  cooking  of,  259 

digestibility  of  various,  256 
diseased,  258 

Mercury,  bichloride  of,  as  a  dis- 
infectant, 339 

Metchnikoff,  theory  of,  58 

Meters,  water,  150 

Micrococci,  varieties  of,  41 

Military  hospitals,  427,  439 
hygiene,  422 


Military  hygiene,  importance  of, 

423 
Milk,  245 

as  a  cause  of  disease,  248 

as  a  source  of  infection,  249- 

252 
care  and  preparation  of,  246 
characteristics   of    good,   253, 

473 
of  lime,  341 

test  for  annotto  in,  477 
for  boric  acid  in,  478 
for  formaldehyde  in,  479 
for  salicylic  acid  in,  478 
to  determine  the  ash  in,  474 
fats  in,  474 
total  sohds  in,  474 
typhoid  fever,  due  to,  250 
use  of  preservatives  in,  253 
Milk-borne  epidemics,  character- 
istics of,  251 
Mines,  atmosphere  of,  93 
Moisture  in  warmed  air,  140 
Morbidity  rates,  456 
Mortality,  cause  of  infant-,  454 
due  to  impurities  in  air,  95 
rate  of  infant-,  454 
Mortality-rate,  typhoid,  an  index 

of  water-purity,  176,  180-182 
Mortality-rates,  453 
Movement  of  heated  air,  113 
Munson  hospital  tent,  440 
Mutton,  256 

N. 

Natural  ventilation.  111 

Nervous  diseases  in  school-chil- 
dren, 314 

Nessler's  reagent,  448 

Nitrates  in  water,  218,  466 
test  for,  466 

Nitrification  of  organic  matters, 
218 

Nitrites  in  water,  218,  467 
tests  for,  467 

Schuyten's,  468 

Nitrogen,  72 

proportion    of,    to    carbon    in 
diet,  236 

Nuts,  266 


INDEX. 


493 


0. 

Oat-meal,  262 

Objections  to  stoves,  127,  131 
Oil-stoves,  133 
Oleomargarine,  479 
Ophthalmia,       contagious,       m 

schools,  327 
Opsonic  index,  61 
Opsonins,  61 
Organic  excretion,  82 

matters  in  water,  218 
Outlets,  location  of  ventilation, 

118 
Overwork,  effects  of,  m  school, 

312 
Oxygen,  72 

absorption  of,  291 
Oysters,  infection  by,  and  clams, 

257 

P. 

Pail-closets,  385 
Pancreatic  digestion,  232 

juice,  232 
Paraform,  345 
Paraformaldehyde,  345 
Parasites,    transmission    of,    by 

water,  176 
Parasitic  bacteria,  50 
Pasteur  filter,  204,  208 
Pathogenic  bacteria,  50 
Pepsin,  action  of,  230 
Percolation     of     ground-water, 

158-160 
Perflation,  113 
Period  of  incubation,  56 
Permissible  impurity  in  air,  105 

in  soil,  159 
Peroxide  of  hydrogen  as  a  disin- 
fectant, 342 
Personal  disinfection,  353 

hygiene,  279 
Petri  dish,  43 
Pettenkofer's   test   for   carbonic 

acid,  462 
Phagocytosis,  theory  of,  58 
Phosphates  in  water,  219 

test  for,  470 
Physical  examination  of  water, 
213 


Physical  training,  aim  of,  294 
Physiology  of  digestion,  226 
Plenum  system,  123,  145 
Plumbing  for  sewage,  387 
Pneumatic  sewerage  system,  384 
Pneumonia,  infectiousness  of,  25 
Poisson's  formula,  445 
Pollution     of     well-water,    161, 

166 
Population,  actual  increment  of, 
448 
daily,  453 
estimation  of,  448 
natural  increment  of,  448 
weekly,  453 
Pork,  256 

Portable  steam  radiator,  133 
Post-hospitals,  426 
Postulates  of  Koch,  54 
Precautions  in  sick-room,  352 
Predisposing  conditions,  33 
Preparation  of  culture-media,  45 
Preservatives,   adulterants  and, 
269 
in  milk,  253 
use  of,   in  foods,  250 
Prismatic    devices,    increased 

lighting  by,  308 
Probable  duration  of  life,  456 
Probation,  camps  of,  377 
Products  of  combustion,  84 
Prophylactic  infection,  68 

intoxication,  68 
Prophylaxis,  33 
Protection  by  vaccination,   379- 

381 
Proteid  food,  functions  of,  222, 
224,  237 
sources  of,  237 
Ptomains,  50 
Ptyalin,  action  of,  228 
Pumping,  effect  of  excessive,  on 
quality  of  water  in  wells,  162, 
163 
Pure  food  and  drugs  act,  provi- 
sions of,  267 
Purification  of  air  by  fire,  104 
of  atmosphere,  75 
of  ground-water,  158 
of  river-water,  155 
of  sewage,  410 


494 


ISDEX. 


Purification  of  subsoil-  or  ground- 
water, 158 
of  water.  178 

by  chemical  treatment,  184 
by  filtration,  187 
by  subsidence,  182 
domestic,  198 

Q. 

QUARAJNTIME,  362 

at    Canadian    and     Mexican 

ports.  376 
conditions  requiring.  367 
history  of.  362,  363 
house.  378 
inland.  376 
laws,  purpose  of,  363 
local.  378 
origin  of,  362-366 
original  meaning  of,  362 
railroad.  378 

regulations  at  ports  of  depar- 
ture. 364 
of  entry.  367-369 

during  vovage.  366 
school,  323 
stations,  location  of,  370 

reqxiisites  for.  370 
treatment  of  cargoes  in.  371 

of  passengers  in.  371 

of  vessels  in.  371-375 
Quarantines,  inspection  of,  376 


B. 


RADLiXT  heat,  126 

Radiating  surface,  estimation  of, 

146 
Radiation,  direct.  143 

direct-indirect.  144 

indirect.  143 
Railroad  quarantine.  378 
Rainfall,   amount   of.   per  acre, 

152 
Rain-water.  151.  152 

cisterns,  154 

conductors.  392 

filtration  of.  153 

softness  of.  154 
Rations,  army,  433-435 


Raw  v^etables,  typhoid  fever 

and,  265 
Receptors,  Ehrlich's.  63 
Recruits,  qualifications  of,  423 
Refuge,  camps  of.  377 
R^jsters,  size  and  location  of, 

139 
R^istration  area.  23 

records,  importance  of,  450 
Relation     of     water-supply     to 

typhoid  fever,  176 
Relative  value  of  foods,  269 
Removal  of  sewage,  382 
Rennin.  230 
Respiration  impurities,  effect  of, 

78 
Respiratory    vitiation,    diseases 

due  to,  97 
Retention  theory  of  Chauveau, 

58 
River-water.  155 

self-purification  of.  155 
Roasting  and  broiling.  260 
Rooms,  final  disinfection  of,  354 
Rubber,  use  of,  as  protective,  302 


Salictlates.  test  for,  in  milk, 

478  ' 

Salicylic  acid,  test  for,  in  milk, 

SaUva,  functions  of,  229 
Sahvary  digestion.  228 
Salts,  food-,  functions  of,  243 

sources  of,  243 
Sand-filters.  188-198 
Sanitary  cordon,  376 
Sanitation.  33 

improved,  results  due  to.  21.  24 
Saprophj-tes.  functions  of,  48 
Schering's  lamps,  346 

method  of  disinfection.  347 
Scliizomycetes,  35 
School  children,  headache  in.  314 
nervous  diseases  in,  314 
prevention  of   infection  of, 

323 
spinal  deformities  in.  316 
vaccination  of.  327 
furniture,  arrangement  of,  317 


INDEX. 


495 


School  furniture,  influence  of,  on 
health,  316 

hygiene,  310 

infirmaries,  326 

pathology,  311 

quarantine,  323 

rooms,  lighting  of,  318 

work,  duration  of,  311,  312 
School-houses,  care  of,  321 

cloak-rooms  in,  319 

construction  of,  318 

cUsinfection  of,  320 

location  of,  320 

ventilation  of,  318 

warming  of,  318 

water-supply  of,  321 
Schools,  contagious  diseases  in, 

323-325 
Sea-bathing,  297 
Seats,  arrangement  of,  in  schools, 

317 
Sedimentation,  182 
Self-study,  importance  of,  280 
SepticEemia,  definition  of,  56 
"Septic-tank"  system  of  sewage 
treatment,  414-419 
advantages  of,  415,  419 
Sewage,  chemical  treatment  of, 
411 

composition  of,  383 

filtration  of,  411 

intermittent,  412 

pail  system  of  removal,  384 

purification  of,  410 

removal  of,  382 

treatment    of,   by   electricity, 
421 
by  irrigation,  413 
by  sub-irrigation,  413 
by   the   "septic-tank"    sys- 
tem, 414 

ultimate  disposal  of,  410 

water-carriage  of,  384 
Sewage-plumbing,  387 

requirements  of,  388 
Sewage-pollution  of  water,   155, 

156 
Sewerage,  ejector  system,  384 

pneumatic  system,  384 

Shone  system,  384 
Sewer-gas,  89 


Sewer-gas,  bacteria  in,  89 

composition  of,  89 

influence  of,  on  health,  102 
Sewer,  405 

advantages  of  "separate,"  407 

"combined,"  406 
shape  of,  407 

construction  of,  406 

"separate,"  407 

specification  for,  408 

ventilation  of,  407,  409 
Shallow  wells,  161 
Shone  sewerage  system,  385 
Sick-rates,  456 
Sick-room,  care  of,  352 

disinfection  of,  353 

impurity  of  air  in,  108 

precautions  in,  352 
Silk  in  clothing,  300 
Size  of  ventilation  inlets,  120 
Skimmed  milk,  248 
Smead    system    of    ventilation, 

118,  319 
Soda,  chlorinated,  338 
Soil,  90 

bacteria  in,  90 

limit  of  permissible   impurity 
in,  159 

purifying  action  of,  155 
Soil-air,  89 

circulation  of,  91 

composition  of,  91 

influence   of,   on   health,    101, 
102 
Soil-pipe,  388 

connection    of,     with     house- 
drain,  390 

location  and  construction  of, 
388 

testing  of,  396 

ventilation  of,  388,  391 
Soldier,  clothing  of,  436,  437 

food  of,  433-436 

instruction  of,  in  hygiene,  440 

work  of,  440 
Soldiers,     weights     carried     by, 

436 
Solids,  total,  in  water,  217 
Soups  and  broths,  260 
Source  of  air-supply,  110 
Sources  of  water-supply,  151 


496 


INDEX. 


Spinal  deformities  in  school  chil- 
dren, 316 
Spirilla,  40 
Spores,  characteristics  of,  39 

formation  of,  39 
Springs,  151,  160 
Spring- water,  160,  165 

purity  of,  161 
Statistical  inquiry,  principles  of, 

444 
Statistics  showing  sanitary  gain, 

22,  23 
Steam,  disinfection  by,  333,  356 
Steam-heating,  143 
Steapsin,  action  of,  233 
Sterihzation,  fractional,  44 

mechanical,  333 

methods  of,  44 

of  apparatus,  44 

of  water  by  boiling,  201 
Sterilized  milk,  253 
Sterilizer,  Forbes,  201 
SteriHzers,  45,  199,  334,  335 
Stimulants,  270 

cautions  in  use  of,  272 

classification  of,  270 

function  of,  270 

indications  for  use  of,  270 
Stoves,  129 

gas-,  131 

gases  from.  129 

objections  to,  130,  131 

oil-,  133 

ventilating,  130 
Studies  in  school,  order  of,  312 
Sub-irrigation,  413 
Subsidence,    water    purification 
,  by,  182 

Subsoil-water,  151,  157 
Sulphate  of  iron,  342 
Sulphur  dioxide,  343,  357 

fimiigation  with,  355 
Sulphuretted  hydrogen,  101 
Sulphurous  acid  gas,    101,   343, 

357 
Surface-water,  151,  155 


Tka,  271 

and  coffee,  abuse  of,  272 
Tents,  hospital,  440 


Tests  of  well-water,  167 
Theory  of  antitoxins,  59 
of  Buchner,  58 
of  Chauveau,  58 
of  Ehrlich,  62 
of  Metchnikoff,  58 
of  opsonins,  61 
of  Pasteur,  58 
of  phagocytosis,  58 
Total  sohds  in  water,  217 
Toxaemia,  definition  of,  56 
Toxalbumins,  50 
Toxins,  50 

Training,  physical,  aim  of,  294 
Transmission  of  heat,  137 
Trap,  bell,  394 
Bower's  394 
Cudell's,  394 
grease,  395 

McClellan's  antisiphoning,  396 
S  or  siphon,  394 
Traps,  393 

seal  of,  393,  395 
siphoning  of,  395 
vent-pipes  for,  395 
Trikresol,  314 
Trillat's  method  of  disinfection, 

346 
Trypsin,  action  of,  232 
Tuberculosis,  due  to  school-life, 
315 
constructive   value   of  fat  in, 

241 
effect  of  dust  in  causing,  95 

of  pure  air  in,  81 
influence  of  heredity  on,  286 

of  sunlight  on,  306 
reduction  in  mortality  rate  of, 
26 
Tubercidin,  249 
Turkish  bath,  287 
Typhoid  fever  and  malaria,  408 
and  raw  vegetables,  265 
due  to  milk,  250 
as  an  index  of  water  j)urity, 

180-182 
dissemination  of,  428-432 
due  to  flies,  429 
epidemics  of,  175 
in  camps,  428-432 
incubation  period  of,  429, 432 


INDEX. 


497 


Typhoid   fever    in    rural    popu- 
lations, l(iS 
Tyrotoxicon,  249 


Vaccination  of  school  children, 
327 
protection  by,  379-381 
statistics,  379-381 
Variety   in   food,    necessity   for, 

225,  244 
Vegetables,     cooking     of,     264, 
265 
typhoid  fever  and  raw,  265 
Velocity  of  air-currents,   114 
Ventilating  apparatus,  116 
grates,  128,  129 
stoves,  130 
Ventilation  and  heating,  103 
artificial,  111,  122 
definition  of,  104 
devices  for,  116 
extent  of,  necessary,  107 
external,  103 
factors  in,  105 
fans,  122,  123 
forces  of.  111 
internal,  104 
natural,  111 
of  school-houses,  318 
of  sewers,  407,  409 
of  soil-pipes,  388,  391 
of  vent-pipes,  395 
of  water-closets,  405 
practical  points  in,  124 
problems,  formula  for,  108 
Smead  system  of,  118 
Ventilators,  113 
Vital  resistance,  value  of,  34 
statistics,    443 
grouping  in,  445 
influence  of,  24 
methods  of  obtaining,  444 
nvunerical  standard  in,  445 

imits  in,  444 
probable  error  in,  446 
value  of,  443 

of  series  in,  446 
variation  in,  445 

32 


W. 

Warmed  air,  humidity  of,  139- 

141 
Warming  of  school-houses,  311 
Waste-pipes,  388 

connection    of,    to    house-fix- 
tures, 392 
with  soil-pipes,  392 
Water,  147 

ammonia  in,  218 

bacterial  examination  of,  215 

boiling  of,  201 

bottle   for   collecting   samples 
of,  465 

chemical  examination  of,  216 
treatment  of,  184 

chlorine  in,  217 

classification  of,  170,  220 

collection  of,  for  analysis,  215 

cost  of  sickness  due  to  pollu- 
ted, 179 

deep-  or  artesian-,  151,  163 

diseases  caused  by  impurities 
in,  171-177 

double  supply  of,  149 

effects  of  impure,  177 

examination  of,  213 

excretion  of,  291 

filtration  of,  187 

ground-  or  subsoil-,  151,  157 

hardness  of,  154,  219 

lake-,  157 

lead  in,  173 

level  oi^  subsoil-,  159 

meters,  150 

nitrates  in,  219 

nitrites  in,  219 

organic  matters  in,  218 

percolation  of,  160 

phosphates  in,  219 

physical  examination  of,  213, 

purification  of,  155,  158,  178 
in  household,  198 

purity  of  subsoil-,  159 

quantity  of,  necessary,  147 

rain-,  151 

river-,  155 

sewage-pollution  of,  155,  156 

sources  of,  151 

spring-,  160-170 


498 


INDEX. 


Water,  spring-,  purity  of,  160- 
165 

storage  of,  182 

surface-,  151,  155 

tests  for  pliysical   properties, 
213,  464 

total  solids  in,  217 

transmission  of  i^arasites  by, 
176 
Water-carriage  of  sewage,  384 
Water-closets,  399 

connection  of,  to  water-supply, 
404 

hopper,  402,  403 

location  of,  405 

pan,  400 

plug  or  plunger,  401,  402 

requisites  for,  399 

siphon,  403 

valve,  400,  401 

ventilation  of,  404 

washout,  400 
Water-purity,  index  of,  179-181 
Water-supply,  infection  of,  174 

of  camps,  433 

of  cities,  148,  171 

of  school-houses,  321 


Water-supply,    relation     of,     to 

typhoid  fever,  168,  169 
Weights  carried  by  soldiers,  436 
Well-water,  pollution  of,  161 

testing  of,  167 
Wells,  area  drained  by,  162,  166 

construction  and  care  of,  165 

deep  or  artesian,  163 

location  of,  161,  166 

shallow,  161 
Welsbach  light,  88 
Wheat,  262 

bread,  characteristics  of,  484 
Wheat-flour,  263 

characteristics  of,  482 
Winds  as  ventilating  agents,  111 
Woollen  clothing,  advantages  of, 

300 
Wright,  opsonic  theory  of,  61 

z. 

Zinc  chloride  as  a  disinfectant, 

341 
Zooglea,  42 
Zymotic  diseases,  51 


DATE  DUE 


COLUMBIA  UNIVERSITY  LIBRARIES 

0041089367 


Histology 


(1) 


